Method for growing single-wall carbon nanotubes utlizing seed molecules

ABSTRACT

This invention relates generally to a method for growing single-wall carbon nanotube (SWNT) from seed molecules. The supported or unsupported SWNT seed materials can be combined with a suitable growth catalyst by opening SWNT molecule ends and depositing a metal atom cluster. In one embodiment, a suspension of seed particles containing attached catalysts is injected into an evaporation zone to provide an entrained reactive nanoparticle. A carbonaceous feedstock gas is then introduced into the nanoparticle stream under conditions to grow single-wall carbon nanotubes. Recovery of the product produced can be done by filtration, centrifugation and the like.

BACKGROUND OF THE INVENTION

[0001] Fullerenes are closed-cage molecules composed entirely ofsp²-hybridized carbons, arranged in hexagons and pentagons. Fullerenes(e.g, C₆₀) were first identified as closed spheroidal cages produced bycondensation from vaporized carbon.

[0002] Fullerene tubes are produced in carbon deposits on the cathode incarbon arc methods of producing spheroidal fullerenes from vaporizedcarbon. Ebbesen et al. (Ebbesen I), “Large-Scale Synthesis Of CarbonNanotubes,” Nature, Vol. 358, p. 220 (Jul. 16, 1992) and Ebbesen et al.,(Ebbesen II), “Carbon Nanotubes,” Annual Review of Materials Science.Vol. 24, p. 235 (1994). Such tubes are referred to herein as carbonnanotubes. Many of the carbon nanotubes made by these processes weremulti-wall nanotubes, i.e., the carbon nanotubes resembled concentriccylinders. Carbon nanotubes having up to seven walls have been describedin the prior art. Ebbesen II; Iijima et al., “Helical Microtubules OfGraphitic Carbon,” Nature, Vol. 354, p. 56 (Nov. 7, 1991).

[0003] Single-wall carbon nanotube have been made in a DC arc dischargeapparatus of the type used in fullerene production by simultaneouslyevaporating carbon and a small percentage of Group VIII transition metalfrom the anode of the arc discharge apparatus. See Iijima et al.,“Single-Shell Carbon Nanotubes of 1 nm Diameter,” Nature, Vol. 363, p.603 (1993); Bethune et al., “Cobalt Catalyzed Growth of Carbon Nanotubeswith Single Atomic Layer Walls,” Nature, Vol. 63, p. 605 (1993); Ajayanet al., “Growth Morphologies During Cobalt Catalyzed Single-Shell CarbonNanotube Synthesis,” Chem. Phys. Lett., Vol. 215, p. 509 (1993); Zhou etal., “Single-Walled Carbon Nanotubes Growing Radially From YC₂Particles,” Appl. Phys. Lett., Vol. 65, p. 1593 (1994); Seraphin et al.,“Single-Walled Tubes and Encapsulation of Nanocrystals Into CarbonClusters,” Electrochem. Soc., Vol. 142, p. 290 (1995); Saito et al.,“Carbon Nanocapsules Encaging Metals and Carbides,” J. Phys Chem.Solids, Vol. 54, p. 1849 (1993); Saito et al., “Extrusion of Single-WallCarbon Nanotubes Via Formation of Small Particles Condensed Near anEvaporation Source,” Chem. Phys. Lett., Vol. 236, p. 419 (1995). It isalso known that the use of mixtures of such transition metals cansignificantly enhance the yield of single-wall carbon nanotubes in thearc discharge apparatus. See Lambert et al., “Improving ConditionsToward Isolating Single-Shell Carbon Nanotubes,” Chem. Phys. Lett., Vol.226, p. 364 (1994).

[0004] While this arc discharge process can produce single-wallnanotubes, the yield of nanotubes is low and the tubes exhibitsignificant variations in structure and size between individual tubes inthe mixture. Individual carbon nanotubes are difficult to separate fromthe other reaction products and purify.

[0005] An improved method of producing single-wall nanotubes isdescribed in U.S. Ser. No. 08/687,665, entitled “Ropes of Single-WalledCarbon Nanotubes” incorporated herein by reference in its entirety. Thismethod uses, inter alia, laser vaporization of a graphite substratedoped with transition metal atoms, preferably nickel, cobalt, or amixture thereof, to produce single-wall carbon nanotubes in yields of atleast 50% of the condensed carbon. The single-wall nanotubes produced bythis method tend to be formed in clusters, termed “ropes,” of 10 to 1000single-wall carbon nanotubes in parallel alignment, held together by vander Waals forces in a closely packed triangular lattice. Nanotubesproduced by this method vary in structure, although one structure tendsto predominate.

[0006] Although the laser vaporization process produces improvedsingle-wall nanotube preparations, the product is still heterogeneous,and the nanotubes are too tangled for many potential uses of thesematerials. In addition, the vaporization of carbon is a high energyprocess and is inherently costly. Therefore, there remains a need forimproved methods of producing single-wall nanotubes of greater purityand homogeneity. Furthermore, many practical materials could make use ofthe properties of singe-wall carbon nanotubes if only they wereavailable as macroscopic components. However, such components have notbeen produced up to now.

SUMMARY OF THE INVENTION

[0007] Accordingly, it is an object of this invention to provide a highyield, single step method for producing large quantities of continuousmacroscopic carbon fiber from single-wall carbon nanotubes usinginexpensive carbon feedstocks at moderate temperatures.

[0008] It is another object of this invention to provide macroscopiccarbon fiber made by such a method.

[0009] It is also an object of this invention to provide a moleculararray of purified single-wall carbon nanotubes for use as a template incontinuous growing of macroscopic carbon fiber.

[0010] It is another object of the present invention to provide a methodfor purifying single-wall carbon nanotubes from the amorphous carbon andother reaction products formed in methods for producing single-wallcarbon nanotubes (e.g., by carbon vaporization).

[0011] It is also an object of the present invention to provide a newclass of tubular carbon molecules, optionally derivatized with one ormore functional groups, which are substantially free of amorphouscarbon.

[0012] It is also an object of this invention to provide a number ofdevices employing the carbon fibers, nanotube molecular arrays andtubular carbon molecules of this invention.

[0013] It is an object of this invention to provide composite materialcontaining carbon nanotubes.

[0014] It is another object of this invention to provide a compositematerial that is resistant to delamination.

[0015] A method for purifying a mixture comprising single-wall carbonnanotubes and amorphous carbon contaminate is disclosed. The methodincludes the steps of heating the mixture under oxidizing conditionssufficient to remove the amorphous carbon, followed by recovering aproduct comprising at least about 80% by weight of single-wall carbonnanotubes.

[0016] In another embodiment, a method for producing tubular carbonmolecules of about 5 to 500 nm in length is also disclosed. The methodincludes the steps of cutting single-wall nanotube containing-materialto form a mixture of tubular carbon molecules having lengths in therange of 5-500 nm and isolating a fraction of the molecules havingsubstantially equal lengths. The nanotubes disclosed may be used,singularly or in multiples, in power transmission cables, in solarcells, in batteries, as antennas, as molecular electronics, as probesand manipulators, and in composites.

[0017] In another embodiment, a method for forming a macroscopicmolecular array of tubular carbon molecules is disclosed. This methodincludes the steps of providing at least about 10⁶ tubular carbonmolecules of substantially similar length in the range of 50 to 500 nm;introducing a linking moiety onto at least one end of the tubular carbonmolecules; providing a substrate coated with a material to which thelinking moiety will attach; and contacting the tubular carbon moleculescontaining a linking moiety with the substrate.

[0018] In another embodiment, another method for forming a macroscopicmolecular array of tubular carbon molecules is disclosed. First, ananoscale array of microwells is provided on a bate. Next, a metalcatalyst is deposited in each microwells. Next, a stream of hydrocarbonor CO feedstock gas is directed at the substrate under conditions thateffect growth of single-wall carbon nanotubes from each microwell.

[0019] In another embodiment, still another method for forming amacroscopic molecular array of tubular carbon molecules is disclosed. Itincludes the steps of providing surface containing purified butentangled and relatively endless single-wall carbon nanotube material;subjecting the surface to oxidizing conditions sufficient to cause shortlengths of broken nanotubes to protrude up from the surface; andapplying an electric field to the surface to cause the nanotubesprotruding from the surface to align in an orientation generallyperpendicular to the surface and coalesce into an array by van der Waalsinteraction forces.

[0020] In another embodiment, a method for continuously growing amacroscopic carbon fiber comprising at least about 10⁶ single-wallnanotubes in generally parallel orientation is disclosed. In thismethod, a macroscopic molecular array of at least about 10⁶ tubularcarbon molecules in generally parallel orientation and havingsubstantially similar lengths in the range of from about 50 to about 500nanometers is provided. The hemispheric fullerene cap is removed fromthe upper ends of the tubular carbon molecules in the array. The upperends of the tubular carbon molecules in the array are then contactedwith a catalytic metal. A gaseous source of carbon is supplied to theend of the array while localized energy is applied to the end of thearray in order to heat the end to a temperature in the range of about500° C. to about 1300° C. The growing carbon fiber is continuouslyrecovered.

[0021] In another embodiment, a macroscopic molecular array comprisingat least about 10⁶ single-wall carbon nanotubes in generally parallelorientation and having substantially similar lengths in the range offrom about 5 to about 500 nanometers is disclosed.

[0022] In another embodiment, a composition of matter comprising atleast about 10⁶ by weight of single-wall carbon nanotubes is disclosed.

[0023] In still another embodiment, macroscopic carbon fiber comprisingat least about 10⁶ single-wall carbon nanotubes in generally parallelorientation is disclosed.

[0024] In another embodiment, an apparatus for forming a continuousmacroscopic carbon fiber from a macroscopic molecular template arraycomprising at least about 10⁶ single-wall carbon nanotubes having acatalytic metal deposited on the open ends of said nanotubes isdisclosed. This apparatus includes a means for locally heating only theopen ends of the nanotubes in the template array in a growth andannealing zone to a temperature in the range of about 500° C. to about1300° C. It also includes a means for supplying a carbon-containingfeedstock gas to the growth and annealing zone immediately adjacent theheated open ends of the nanotubes in the template array. It alsoincludes a means for continuously removing growing carbon fiber from thegrowth and annealing zone while maintaining the growing open end of thefiber in the growth and annealing zone.

[0025] In another embodiment, a composite material containing nanotubesis disclosed. This composite material includes a matrix and a carbonnanotube material embedded within said matrix.

[0026] In another embodiment, a method of producing a composite materialcontaining carbon nanotube material is disclosed. It includes the stepsof preparing an assembly of a fibrous material; adding the carbonnanotube material to the fibrous material; and adding a matrix materialprecursor to the carbon nanotube material and the fibrous material.

[0027] In another embodiment, a three-dimensional structure ofderivatized single-wall nanotube molecules that spontaneously form isdisclosed. It includes several component molecule having multiplederivatives brought together to assemble into the three-dimensionalstructure.

[0028] The foregoing objectives, and others apparent to those skilled inthe art, are achieved according to the present invention as describedand claimed herein.

BRIEF DESCRIPTION OF THE DRAWINGS

[0029]FIG. 1 is a diagram of an apparatus for practicing the invention.

[0030]FIG. 2 is a diagram of an apparatus for practicing the inventionutilizing two different laser pulses to vaporize the composite rodtarget.

[0031]FIG. 3A is a TEM spectrum of purified SWNTs according to thepresent invention.

[0032]FIG. 3B is a SEM spectrum of purified SWNTs according to thepresent invention.

[0033]FIG. 3C is a Raman spectrum of purified SWNTs according to thepresent invention.

[0034]FIG. 4 is a schematic representation of a portion of anhomogeneous SWNT molecular array according to the present invention.

[0035]FIG. 5 is a schematic representation of an heterogeneous SWNTmolecular array according to the present intention.

[0036]FIG. 6 is a schematic representation of the growth chamber of thefiber apparatus according-to the present invention.

[0037]FIG. 7 is a schematic representation of the pressure equalizationand collection zone of the fiber apparatus according to the presentinvention.

[0038]FIG. 8 is a composite array according to the present invention.

[0039]FIG. 9 is a composite array according to the present invention.

[0040]FIG. 10 is a power transmission cable according to the presentinvention.

[0041]FIG. 11 is a schematic representation of a bistable, nonvolatilenanoscale memory device according to the present invention

[0042]FIG. 12 is a graph showing the energy wells that correspond toeach of the bistable states in the memory bit of FIG. 11.

[0043]FIG. 13 is a schematic representation of a lithium ion secondarybattery according to the present invention.

[0044]FIG. 14 is an anode for a lithium ion battery according to thepresent invention.

[0045]FIG. 15A is a medium-magnification transmission electronmicroscope image of single-wall nanotubes.

[0046]FIG. 15B is a high-magnification image of adjacent single-wallcarbon nanotubes.

[0047]FIG. 15C is a high-magnification image of adjacent single-wallcarbon nanotubes.

[0048]FIG. 15D is a high-magnification image of adjacent single-wallcarbon nanotubes.

[0049]FIG. 15E is a high-magnification image of the cross-section ofseven adjacent single-wall carbon nanotubes.

[0050]FIG. 16A is a scanning electron microscope (SEM) image of rawsingle-walled fullerene nanotube felt.

[0051]FIG. 16B is a SEM image of the single-walled fullerene nanotubefelt material of FIG. 16A after purification.

[0052]FIG. 16C is a SEM image of the single-walled fullerene nanotubefelt after tearing, resulting in substantial alignment of thesingle-walled nanotube rope fibers.

[0053]FIG. 17 is an atomic force microscopy image of cut fullerenenanotubes deposited on highly oriented pyrolytic graphite.

[0054]FIG. 18A is a graph of field flow fractionation (FFF) of a cutnanotubes suspension.

[0055]FIG. 18B represents the distribution of fullerene nanotubeslengths measured by AFM on three collections.

[0056]FIG. 19 shows an AFM image of a fullerene nanotube “pipe” tetheredto two 10 nm gold spheres.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0057] Carbon has from its very essence not only the propensity toself-assemble from a high temperature vapor to form perfect spheroidalclosed cages (of which C₆₀ is prototypical), but also (with the aid of atransition metal catalyst) to assemble into perfect single-wallcylindrical tubes which may be sealed perfectly at both ends with asemifullerene dome. These tubes, which may be thought of asone-dimensional single crystals of carbon, are true fullerene molecules,having no dangling bonds.

[0058] Single-wall carbon nanotubes of this invention are much morelikely to be free of defects than multi-wall carbon nanotubes. Defectsin single-wall carbon nanotubes are less likely than defects inmulti-walled carbon nanotubes because the latter can survive occasionaldefects, while the former have no neighboring walls to compensate fordefects by forming bridges between unsaturated carbon valances. Sincesingle-wall carbon nanotubes will have fewer defects, they are stronger,more conductive, and therefore more used than multi-wall carbonnanotubes of similar diameter.

[0059] Carbon nanotubes, and in particular the single-wall carbonnanotubes of this invention, are useful for making electrical connectorsin micro devices such as integrated circuits or in semiconductor chipsused in computers because of the electrical conductivity and small sizeof the carbon nanotube. The carbon nanotubes are useful as antennas atoptical frequencies, and as probes for scanning probe microscopy such asare used in scanning tunneling microscopes (STM) and atomic forcemicroscopes (AFM). The carbon nanotubes may be used in place of or inconjunction with carbon black in tires for motor vehicles. The carbonnanotubes are also useful as supports for catalysts used in industrialand chemical processes such as hydrogenation, reforming and crackingcatalysts.

[0060] Ropes of single-wall carbon nanotubes made by this invention aremetallic, i.e., they will conduct electrical charges with a relativelylow resistance. Ropes are useful in any application where an electricalconductor is needed, for example as an additive in electricallyconductive paints or in polymer coatings or as the probing tip of anSTM.

[0061] In defining carbon nanotubes, it is helpful to use a recognizedsystem of nomenclature. In this application, the carbon nanotubenomenclature described by M. S. Dresselhaus, G. Dresselhaus, and P. C.Eklund, Science of Fullerness and Carbon Nanotubes, Chap. 19, especiallypp. 756-760, (1996), published by Academic Press, 525 B Street, Suite1900, San Diego, Calif. 92101-4495 or 6277 Sea Harbor Drive, Orlando,Fla. 32877 (ISBN 0-12-221820-5), which is hereby incorporated byreference will be used. The single wall tubular fullerenes aredistinguished from each other by double index (n, m) where n and m areintegers that describe to cut a single ship of hexagonal “chicken-wire”graphite so that it makes the tube perfectly when it is wrapped onto thesurface of a cylinder and the edges are sealed together. When the twoindices are the same, m=n, the resultant tube is said to be of the“arm-chair” (or n, n) type, since when the tube is cut perpendicular tothe tube axis only the sides of the hexagons are exposed and theirpattern around the periphery of the tube edge resembles the arm and seatof an arm chair repeated n times. Arm-chair tubes are a preferred formof single-wall carbon nanotubes since they are metallic, and haveextremely high electrical and thermal conductivity. In addition, allsingle-wall nanotubes have-extremely high tensile strength.

[0062] The dual laser pulse feature described herein produces anabundance of (10, 10) single-wall carbon nanotubes. The (10, 10),single-wall carbon nanotubes have an approximate tube diameter of 13.8Å±0.3 Å or 13.8 Å±0.2 Å.

[0063] The present invention provides a method for making single-wallcarbon nanotubes in which a laser beam vaporizes material from a targetcomprising, consisting essentially of consisting of a mixture of carbonand one or more Group VI or Group VIII transition metals. The vapor fromthe target of those, the (10, 10) tube is predominant. The method alsoproduces significant amounts of single-wall carbon nanotubes that arearranged as ropes, i.e., the single-wall carbon nanotubes run parallelto each other. Again, the (10, 10) tube is the predominant tube found ineach rope. The laser vaporization method provides several advantagesover the arc discharge method of making carbon nanotubes: laservaporization allows much greater control over the conditions favoringgrowth of single-wall carbon nanotubes, the laser vaporization methodpermits continuous operation, and the laser vaporization method producessingle-wall carbon nanotubes in higher yield and of better quality. Asdescribed herein, the laser vaporization method may also be used toproduce longer carbon nanotubes and longer ropes.

[0064] Carbon nanotubes may have diameters ranging from about 0.6nanometers (nm) for a single-wall carbon nanotube up to 3 nm, 5 nm, 10nm, 30 nm, 60 nm or 100 nm for single-wall or multi-wall carbonnanotubes. The carbon nanotubes may range in length from 50 nm up to 1millimeter (mm), 1 centimeter (cm), 3 cm, 5 cm, or greater. The yield ofsingle-wall carbon nanotubes in the product made by this invention isunusually high. Yields of single-wall carbon nanotubes greater than 10wt %, greater than 30 wt % and greater than 50 wt % of the materialvaporized are possible with this invention.

[0065] As will be described further, the one or more Group VI or VIIItransition metals catalyze the growth in length of a carbon nanotubeand/or the ropes. The one or more Group VI or VIII transition metalsalso selectively produce single-wall carbon nanotubes and ropes ofsingle-wall carbon nanotubes in high yield. The mechanism by which thegrowth in the carbon nanotube and/or rope is accomplished is notcompletely understood. However, it appears that the presence of the oneor more Group VI or VIII transition metals on the end of the carbonnanotube facilitates the addition of carbon from the carbon vapor to thesolid structure that forms the carbon nanotube. Applicants believe thismechanism is responsible for the high yield and selectivity ofsingle-wall carbon nanotubes and/or ropes in the product and willdescribe the invention utilizing this mechanism as merely an explanationof the results of the invention. Even if the mechanism is provedpartially or wholly incorrect, the invention which achieves theseresults is still fully described herein.

[0066] One aspect of the invention comprises a method of making carbonnanotubes and/or ropes of carbon nanotubes which comprises supplyingcarbon vapor to the live end of a carbon nanotube wile maintaining thelive end of a carbon nanotubes in annealing zone. Carbon can bevaporized in accordance with this invention by an apparatus in which alaser beam impinges on a target comprising carbon that is maintained ina heated zone. A similar apparatus has been described in the literature,for example, in. U.S. Pat. No. 5,300,203 which is incorporated herein byreference, and in Chai, et al., “Fullerenes with Metals Inside.” J.Phys. Chem., vol. 95, no. 20, p. 7564 (1991).

[0067] Carbon nanotubes having at least one live end arc formed when thetarget also comprises a Group VI or VIII transition metal or mixtures oftwo or more Group VI or VIII transition metals. In this application, theterm “live end” of a carbon nanotube refers to the end of the carbonnanotube on which atoms of the one or more Group VI or VIII transitionmetals are located. One or both ends of the nanotube may be a live end.A carbon nanotube having a live end is initially produced in the laservaporization apparatus of this invention by using a laser beam tovaporize material from a target comprising carbon and one or more GroupVI or VIII transition metals and then introducing the carbon/Group VI orVIII transition metal vapor to an annealing zone. Optionally, a secondlaser beam is used to assist in vaporizing carbon from the target. Acarbon nanotube having a live end will form in the annealing zone andthen grow in length by the catalytic addition of carbon from the vaporto the live end of the carbon nanotube. Additional carbon vapor is thensupplied to the live end of a carbon nanotube to increase the length ofthe carbon nanotube.

[0068] The carbon nanotube that is formed is not always a single-wallcarbon nanotube; it may be a multi-wall carbon nanotube having two,five, ten or any greater number of walls (concentric carbon nanotubes).Preferably, though, the carbon nanotube is a single-wall carbon nanotubeand this invention provides a way of selectively producing (10, 10)single-wall carbon nanotubes in greater and sometimes far greaterabundance than multi-wall carbon nanotubes.

[0069] The annealing zone where the live end of the carbon nanotube isinitially formed should be maintained at a temperature of 500° to 1500°C., more preferably 1000° to 1400° C. and most preferably 1100 to 1300°C. In embodiments of this invention where carbon nanotubes having liveends are caught and maintained in an annealing zone and grown in lengthby further addition of carbon (without the necessity of adding furtherGroup VI or VIII transition metal vapor), the annealing zone may becooler, 400° to 1500° C., preferably 400° to 1200° C., most preferably500° to 700° C. The pressure in the annealing zone should be maintainedin the range of 50 to 200 Torr., more preferably 100 to 800 Torr. andmost preferably 300 to 600 Torr. The atmosphere in the annealing zonewill comprise carbon. Normally, the atmosphere in the annealing zonewill also comprise a gas that sweeps the carbon vapor through theannealing zone to a collection zone. Any gas that does not prevent theformation of carbon nanotubes will work as the sweep gas, but preferablythe sweep gas is an inert gas such as helium, neon, argon, krypton,xenon, radon, or mixtures of two or more of these. Heliun and Argon aremost preferred. The use of a flowing inert gas provides the ability tocontrol temperature, and more importantly, provides the ability totransport carbon to the live end of the carbon nanotube. In someembodiments of the invention, when other materials are being vaporizedalong with carbon, for example one or more Group VI or VI transitionmetals, those compounds and vapors of those compounds will also bepresent, in the atmosphere of the annealing zone. If a pure metal isused, the resulting vapor will comprise the metal. If a metal oxide isused, the resulting vapor will comprise the metal and ions or moleculesof oxygen.

[0070] It is important to avoid the presence of too many materials thatkill or significantly decrease the catalytic activity of the one or moreGroup VI or VIII transition metals at the live end of the carbonnanotube. It is known that the presence of too much water (H₂O) and/oroxygen (O₂) will kill or significantly decrease the catalytic activityof the one or more Group VI or VIII transition metals. Therefore, waterand oxygen are preferably excluded from the atmosphere in the annealingzone. Ordinarily, the use of a sweep gas having less than 5 wt %, morepreferably less than 1 wt % water and oxygen will be sufficient. Mostpreferably the water and oxygen will be less than 0.1 wt %.

[0071] Preferably, the formation of the carbon nanotube having a liveend and the subsequent addition of carbon vapor to the carbon nanotubeare all accomplished in the same apparatus. Preferably, the apparatuscomprises a laser that is aimed at a target comprising carbon and one ormore Group VI or VIII transition metals, and the target and theannealing zone are maintained at the appropriate temperature, forexample by maintaining the annealing zone in an oven. A laser beam maybe aimed to impinge on a target comprising carbon and one or more GroupVI or VIII transition metals where the target is mounted inside a quartztube that is in turn maintained within a furnace maintained at theappropriate temperature. As noted above, the oven temperature is mostpreferably within the range of 1100° to 1300° C. The tube need notnecessarily be a quartz tube; it may be made from any material tat canwithstand the temperatures (1000° to 1500° C.). Alumina or tungstencould be used to make the tube in addition to quartz.

[0072] Improved results are obtained where a second laser is also aimedat the target and both lasers are timed to deliver pulses of laserenergy at separate times. For example, the first laser may deliver apulse intense enough to vaporize material from the surface of thetarget. Typically, the pulse from the first laser will last about 10nanoseconds (ns). After the first pulse has stopped, a pulse from asecond laser hits the target or the carbon vapor or plasma created bythe first pulse to provide more uniform and continued vaporization ofmaterial from the surface of the target. The second laser pulse may bethe same intensity as the first pulse, or less intense, but the pulsefrom the second laser is typically more intense than the pulse from thefirst laser, and typically delayed about 20 to 60 ns, more preferably 40to 55 ns, after the end of the first pulse.

[0073] Examples of a typical specification for the first and secondlasers are given in Examples 1 and 3, respectively. As a rough guide,the first laser may vary in wavelength from 11 to 0.1 micrometers, inenergy from 0.05 to 1 Joule and in repetition frequency from 0.01 to1000 Hertz (Hz). The duration of the first laser pulse may vary from10⁻¹³ to 10⁻⁶ seconds (s). The second laser may vary in wavelength from11 to 0.1 micrometers, in energy from 0.05 to 1 Joule and in repetitionfrequency from 0.01 to 1000 Hertz. The duration of the second laserpulse may vary from 10⁻¹³ s to 10⁻⁶ s. The beginning of the second laserpulse should be separated from end of the first laser pulse by about 10to 100 ns. If the laser supplying the second pulse is an ultraviolet(UV) laser (an Excimer laser for example), the time delay can be longer,up to 1 to 10 milliseconds. But if the second pulse is from a visible orinfrared (IR) laser, then the adsorption is preferably into theelectrons in the plasma created by the first pulse. In this case, theoptimum time delay between pulses is about 20 to 60 ns, more preferably40 to 55 ns and most preferably 40 to 50 ns. These ranges on the firstand second lasers are for beams focused to a spot on the targetcomposite rod of about 0.3 to 10 mm diameter. The time delay between thefirst and second laser pulses is accomplished by computer control thatis known in the art of utilizing pulsed lasers. Applicants have used aCAMAC crate from LeCroy Research Systems, 700 Chestnut Ridge Road,Chestnut Ridge, N.Y. 10977-6499 along with a timing pulse generator fromKinetics Systems Corporation, 11 Maryknoll Drive, Lockport, Ill. 60441and a nanopulser from LeCroy Research Systems. Multiple first lasers andmultiple second lasers may be needed for scale up to larger targets ormore powerful lasers may be used. The main feature of multiple lasers isthat the first laser should evenly ablate material from the targetsurface into a vapor or plasma and the second laser should depositenough energy into the ablated material in the vapor or plasma plumemade by the first pulse to insure that the material is vaporized intoatoms or small molecules (less tan ten carbon atoms per mole). If thesecond laser pulse arrives too soon after the first pulse, the plasmacreated by the first pulse may be so dense that the second laser pulseis reflected by the plasma. If the second laser pulse arrives too lateafter the first pulse, the plasma and/or ablated material created by thefirst laser pulse will strike the surface of the target. But if thesecond laser pulse is timed to arrive just after the plasma and/orablated material has been formed, as described herein, then the plasmaand/or ablated material will absorb energy from the second laser pulse.Also, it should be noted that the sequence of a first laser pulsefollowed by a second laser pulse will be repeated at the same repetitionfrequency as the first and second laser pulses, i.e., 0.01 to 1000 Hz.

[0074] In addition to lasers described in the Examples, other examplesof lasers useful in this invention include an XeF (365 nm wavelength)laser, an XeCl (308 mn wavelength) laser, a KrF (248 nm wavelength)laser or an ArF (193 nm wavelength) laser.

[0075] Optionally, but preferably, a sweep gas is introduced to the tubeupstream of the target and flows past the target carrying vapor from thetarget downstream. The quartz tube should be maintained at conditions sothat the carbon vapor and the one or, more Group VI or VIII transitionmetals will form carbon nanotubes at a point downstream of the carbontarget but still within the heated portion of the quartz tube.Collection of the carbon nanotubes that form in the annealing zone maybe facilitated by maintaining a cooled collector in the internal portionof the far downstream end of the quartz tube. For example, carbonnanotubes may be collected on a water cooled metal structure mound inthe center of the quartz tube. The carbon nanotubes will collect wherethe conditions are appropriate, preferably on the water cooledcollector.

[0076] Any Group VI or VIII transition metal may be used as the one ormore Group VI or, VIII transition metals in this invention. Group VItransition metals are chromium (Cr), molybdenum (Mo), and tungsten (W).Group VIII transition metals are iron (Fe), cobalt (Co), nickel (Ni),ruthenium (Ru), rhodium (Rh), palladium (Pd), osmium (Os), Iridium (Ir)and platinum (Pt). Preferably, the one or more Group VIII transitionmetals are selected from the group consisting of iron, cobalt,ruthenium, nickel and platinum. Most preferably, mixtures of cobalt andnickel or mixtures of cobalt and platinum are used. The one or moreGroup VI or VIII transition metals useful in this invention may be usedas pure metal, oxides of meals, carbides of metals, nitrate salts ofmetals, or other compounds containing the Group VI or VIII transitionmetal. Preferably the one or more Group VI or VIII transition metals areused a pure metals, oxides of metals, or nitrate salts of metals. Theamount of the one or more Group VI or VIII transition metals that shouldbe combined with carbon to facilitate production of carbon nanotubeshaving a live end, is from 0.1to 10,atom percent more preferably 0.5 to5 atom per cent and most preferably 0.5 to 1.5 atom per cent. In thisapplication, atom per cent means the percentage of specified atoms inrelation to the total number of atoms preset. For example, a 1 atom %mixture of nickel and carbon means that of the total number of atoms ofnickel plus carbon 1% are nickel (and the other 99% are carbon). Whenmixtures of two or more Group VI or VIII transition metals are used,each metal should be 1 to 99 atom % of the metal mix, preferably 10 to90 atom % of the metal mix and most preferably 20 to 80 atom % of themetal mix. When two Group VI or VIII transition metals are used, eachmetal is most preferably 30to 70 atom % of the metal mix. When threeGroup VI or VIII transition metals are used, each metal is mostpreferably 20 to 40 atom % of the metal mix.

[0077] The one or more Group VI or VIII transition metals should becombined with carbon to form a target for vaporization by a laser asdescribed herein. The remainder of the target should be carbon and mayinclude carbon in the graphitic form, carbon in the fullerene form,carbon in the diamond form, or carbon in compound form such as polymersor hydrocarbons, or mixtures of two or more of these. Most preferably,the carbon used to make the target is graphite.

[0078] Carbon is mixed with the one or more Group VI or VIII transitionmetals in the ratios specified and then, in the laser vaporizationmethod, combined to form a target that comprises the carbon and the oneor more Group VI or VIII transition metals. The target may be made byuniformly mixing carbon and the one or more Group VI or VIII transitionmetals with carbon cement at room temperature and then placing themixture in a mold. The mixture in the mold is then compressed and heatedto about 130° C. for about 4 or 5 hours while the epoxy resin of thecarbon cement cures. The compression pressure used should be sufficientto compress the mixture of graphite, one or more Group VI or VIIItransition metals and carbon cement into a molded form that does nothave voids so that the molded form will maintain structural integrity.The molded form is then carbonized by slowly heating to a temperature of810° C. for about 8 hours under an atmosphere of flowing argon. Themolded and carbonized targets are then heated to about 1200° C. underflowing argon for about 12 hours prior to their use as a target togenerate a vapor comprising carbon and the one or more Group VI or VIIItransition metals.

[0079] The invention may be further understood by reference to FIG. 1which is a cross-section view of laser vaporization in an oven. A target10 is positioned within tube 12. The target 10 will comprise carbon andmay comprise one or more Group VI or VIII transition metals. Tube 12 ispositioned in oven 14 which comprises insulation 16 and heating elementzone 18. Corresponding portions of oven 14 are represented by insulation16′ and heating element zone 18′. Tube 12 is positioned in oven 14 sothat target 10 is within heating element zone 18.

[0080]FIG. 1 also shows water cooled collector 20 mounted inside tube 12at the downstream end 24 of tube 12. An inert gas such as argon orhelium may be introduced to the upstream end 22 of tube 12 so that flowis from the upstream end 22 of tube 12 to the downstream end 24. A laserbeam 26 is produced by a laser (not, shown) focused on target 10. Inoperation, oven 14 is heated to the desired temperature, preferably1100° to 1300° C., usually about 1200° C. Argon is introduced to the end22 as a sweep gas. The argon may optionally be preheated to a desiredtemperature, which should be about the same as the temperature of oven14. Laser beam 26 strikes target 10 vaporizing material in target 10.Vapor from target 10 is carried toward the downstream end 24 by theflowing argon stream. If the target is comprised solely of carbon, thevapor formed will be a carbon vapor. If one or more Group VI or VIIItransition metals are included as part of the target, the vapor willcomprise carbon and one or more Group VI or VIII transition metals.

[0081] The heat from the oven and the flowing argon maintain a certainzone within the inside of the tube as an annealing zone. The volumewithin tube 12 in the section marked 28 in FIG. 1 is the annealing zonewherein carbon vapor begins to condense and then actually condenses toform carbon nanotubes. The water cooed collector 20 may be maintained ata temperature of 700° C. or lower, preferably 50° C. or lower on thesurface to collect carbon nanotubes that were formed in the annealingzone.

[0082] In one embodiment of the invention, carbon nanotubes having alive end can be caught or mounted on a tungsten wire in the annealingzone portion of tube 12. In this embodiment, it is not necessary tocontinue to produce a vapor having one or more Group VI or VIIItransition metals. In this case, target 10 may be switched to a targetthat comprises carbon but not any Group VI or VIII transition metal, andcarbon will be added to the live end of the carbon nanotube.

[0083] In another embodiment of the invention, when the target comprisesone or more Group VI or VIII transition metals, vapor formed by laserbeam 26 will comprise carbon and the one or more Group VI or VIIItransition metals. That vapor will form carbon nanotubes in theannealing zone that will then be deposited on water cooled collector 20,preferably at tip 30 of water cooled collector 20. The presence of oneor more m VI or VIII transition metals in the vapor along with carbon inthe vapor preferentially forms carbon nanotubes instead of fullerenes,although some fullerenes and graphite will usually be formed as well. Inthe annealing zone, carbon from the vapor is selectively added to thelive end of the carbon nanotubes due to the catalytic effect of the oneor more Group VI or VIII transition metals present at the live end ofthe carbon nanotubes.

[0084]FIG. 2 shows an optional embodiment of the invention that can beused to make longer carbon nanotubes wherein a tungsten wire 32 isstretched across the diameter of tube 12 downstream of target 10 butstill within the annealing zone. After laser beam pulses hit the target10 forming a carbon/Group VI or VIII transition metal vapor, carbonnanotubes having live ends will form in the vapor. Some of those carbonnanotubes will be caught on the tungsten wire and the live end will beaimed toward the downstream end 24 of tube 12. Additional carbon vaporwill make the carbon nanotube grow. Carbon nanotubes as long as theannealing zone of the apparatus can be made in this embodiment. In thisembodiment, it is possible to switch to an all carbon target afterinitial formation of the carbon having a live end because the vapor needonly contain carbon at that point.

[0085]FIG. 2 also shows part of second laser beam 34 impacts on target10. In practice, laser beam 26 and second laser beam 34 would be aimedat the same surface of target 10, but they would impact surface atdifferent times as described herein.

[0086] It is also possible to stop the laser or lasers altogether. Oncethe single-wall carbon nanotube having a live end is formed, the liveend will catalyze growth of the single-wall carbon nanotube at lowertemperatures and with other carbon sources. The carbon source can beswitched to fullerenes, that can be transported to the live end by theflowing sweep gas. The carbon source can be graphite particles carriedto the live end by the sweep gas. The carbon source can be a hydrocarbonthat is cared to the live end by a sweep gas or a hydrocarbon gas ormixture of hydrocarbon gasses introduced to tube 12 to flow past thelive end. Hydrocarbons useful include methane, ethane, propane, butane,ethylene, propylene, benzene, toluene or any other paraffinic, olefinic,cyclic or aromatic hydrocarbon, or any other hydrocarbon.

[0087] The annealing zone temperature in this embodiment can be lowerthan the annealing zone temperatures necessary to initially form thesingle-wall carbon nanotube having a live end. Annealing zonetemperatures can be in the range of 400° to 1500° C., preferably 400 to1200° C., most preferably 500° to 700° C. The lower temperatures areworkable because the Group VI or VII transition metal(s) catalyze theaddition of carbon to the nanotube at these lower temperatures

[0088] Measurements show that the single wall carbon nanotubes in theropes have a diameter of 13.8 Å±0.2Å. A (10,10) single-wall carbonnanotubes in the a calculated diameter of about 13.6Å, and themeasurements on the single-wall carbon nanotubes in the ropes provesthey are predominantly the (10,10) tube. The number of single-wallcarbon nanotubes in each rope may vary from about 5 to 5000, preferablyabout 10 to 1000, or 50 to 1000, and most preferably about 100 to 500.The diameters of the ropes range from about 20 to 200Å, more preferablyabout 50 to 200Å. The (10,10) single-wall carbon nanotube predominatesthe tubes in the ropes made by this invention. Ropes having greater than10%, greater than 30%, greater than 50%, greater than 75%, and evengreater than 90% (10,10) single-wall carbon nanotubes have beenproduced. Ropes having greater than 50% greater than 75% and greaterthan 90% armchair (n,n) single-wall carbon nanotubes are also made byand are a part of this invention. The single-wall carbon nanotubes ineach rope are arranged to form a rope having a 2-D triangular latticehaving a lattice constant of about 17Å. Ropes of 0.1 up to 10, 100 or1,000 microns in length are made by the invention. The resistivity of arope made in accordance with this invention was measured to be 0.34 to1.0 micro ohms per meter at 27° C. providing that the ropes aremetallic.

[0089] A “felt” of the ropes described above may also be produced. Theproduct material is collected as a tangled collection of ropes stucktogether in a mat referred to herein as a “felt”. The felt materialcollected from the inventive process has enough strength to withstandhandling, and it has been measured to be electrically conductive. Feltsof 10 mm², 100 mm², 1000 mm² or greater, are formed in the inventiveprocess.

[0090] One advantage of the single-wall carbon nanotubes produced withthe laser vaporization in an oven method is their cleanliness. Typicaldischarge arc-produced single-wall carbon nanotubes are covered with athick layer of amorphous carbon, perhaps limiting their usefulnesscompared to the clean bundles of single-wall carbon nanotubes producedby the laser vaporization method. Other advantages and features of theinvention are apparent from the disclosure. The invention may also beunderstood by reference to Guo et al., “Catalytic Growth OfSingle-Walled Nanotubes By Laser Vaporization,” Chem Phys. Lett. Vol.243, pp. 49-54 (1995)

[0091] The advantages achieved by the dual pulsed lasers insure that thecarbon and metal go through the optimum annealing conditions. The duallaser pulse process achieves this by using time to separate the ablationfrom the further and full vaporization of the ablated material. Thesesame optimum conditions can be achieved by using solar energy tovaporize carbon and metals as described in U.S. application Ser. No.08/483, 045 filed Jun. 7, 1995 which is incorporated herein byreference. Combining any of the group VI or VIII transition metals inplace of the metals disclosed in the 08/483,045 application will producethe single-wall carbon nanotubes and the ropes of this invention.

[0092] Purification of Single-Wall Nanotubes

[0093] Carbon nanotubes in material obtained according to any of theforegoing methods may be purified according to the methods of thisinvention. A mixture containing at least a portion of single-wallnanotubes (“SWNT”) may be prepared, for example, as described by Iijima,et al, or Bethune, et al. However, production methods which producesingle-wall nanotubes in relatively high yield are preferred. Inparticular, laser production methods such as those disclosed in U.S.Ser. No. 08/687,655, may produce up to 70% or more single-wallnanotubes, and the single-wall nanotubes are predominately of thearm-chair structure.

[0094] The product of a typical proces for making mixtures containingsingle-wall carbon nanotubes is a tangled felt which can includedeposits of amorphous carbon, graphite, metal compounds (e.g., oxides),spherical fullerenes, catalyst particles (often coated with carbon orfullerenes) and possibly multi-wall carbon nanotubes. The single-wallcarbon nanotubes may be aggregated in “ropes” of bundles of essentiallyparallel nanotubes.

[0095] When material having a high proportion of single-wall nanotubesis purified as described herein, the preparation produced will beenriched in single-wall nanotubes, so that the single-wall nanotubes aresubstantially free of other material. In particular, single-wallnanotubes will make up at least 80% of the preparation, preferably atleast 90%, more preferably at least 95% and most preferably over 99% ofthe material in the purified preparation.

[0096] The purification process of the present invention comprisesheating the SWNT-containing felt under oxidizing conditions to removethe amorphous carbon deposits and other contaminating materials. In apreferred mode of this purification procedure, the felt is heated in anaqueous solution of an inorganic oxidant, such as nitric acid, a mixtureof hydrogen peroxide and sulfuric acid, or potassium permanganate.Preferably, SWNT-containing felts are refluxed in an aqueous solution ofan oxidizing acid at a concentration high enough to etch away amorphouscarbon deposits within a practical time frame, but not so high that thesingle-wall carbon nanotube material will be etched to a significantdegree. Nitric acid at concentrations from 2.0 to 2.6 M have been foundto be suitable. At atmospheric pressure, the reflux temperature of suchas aqueous acid solution is about 120° C.

[0097] In a preferred process, the nanotube-containing felts can berefluxed in a nitric acid solution at a concentration of 2.6 M for 24hours. Purified nanotubes may be recovered from the oxidizing acid byfiltration through, e.g., a 5 micron pore size TEFLON filter, likeMillipore Type LS. Preferably, a second 24 hour period of refluxing in afresh nitric solution of the same concentration is employed followed byfiltration as described above.

[0098] Refluxing under acidic oxidizing conditions may result in theesterification of some of the nanotubes, or nanotube contaminants. Thecontaminating ester material may be removed by saponification, forexample, by using a saturated sodium hydroxide solution in etanol atroom temperature for 12 hours. Other conditions suitable forsaponification of any ester linked polymers produced in the oxidizingacid treatment will be readily apparent to those skilled in the art.Typically the nanotube preparation, will be neutralized after thesaponification step. Refluxing the nanotubes in 6M aqueous hydrochloricacid for 12 hours has been found to be suitable for neutralization,although other suitable conditions will be apparent to the skilledartisan.

[0099] After oxidation, and optionally sap on and-neutralization, thepurified nanotubes may be collected by settling or filtration preferablyin the form of a thin mat of purified fibers made of ropes,or bundles ofSWNTs, referred to hereinafter as “buck paper.” In a typical example,filtration-of the purified and neutralized nonatubes on a TEFLONmembrane with S micron pore size produced a black mat of purifiednanotubes about 100 microns thick. The nanotubes in the bucky paper maybe of varying lengths and may consists of individual nanotubes, orbundles or ropes of up to 10³ single-wall nanotubes, or mixtures ofindividual single-wall nanotubes and ropes of various thicknesses.Alternatively, bucky paper may be made up of nanotubes which arehomogeneous in length or diameter and/or molecular structure due tofractionation as described hereinafter.

[0100] The purified nanotubes or bucky paper are finally dried, forexample, by baking at 850° C. in a hydrogen gas atmosphere, to producedry, purified nanotube preparations.

[0101] When laser-produced single-wall nanotube material, produced bythe two-laser method of U.S. Ser. No. 08/687,665, was subjectedrefluxing in 2.6 M aqueous nitric acid, with one solvent exchange,followed by sonication in saturated NaOH in ethanol at room temperaturefor 12 hours, then neutralization by refluxing in 6M aqueous HCI for 12hours, removal from the aqueous medium and baking in a hydrogen gasatmosphere at 850° C. in 1 atm H₂ gas (flowing at 1-10 sccm through a 1″quartz tube) for 2 hours, detailed TEM, SEM and Raman spectralexamination showed it to be >99% pure, with the dominant impurity beinga few carbon-encapsulated Ni/Co particles. (See FIGS. 3A, 3B, 3C)

[0102] In another embodiment, a slightly basic solution (e.g., pH ofapproximately 8-12) may also be used in the saponification step. Theinitial cleaning in 2.6 M HNO₃ converts amorphous carbon in the rawmaterial to various sizes of linked polycyclic compounds such as fulvicand humic acids, as well as larger polycyclic aromatics with variousfunctional groups around the periphery, especially the carboxylic acidgroups. The base solution ionizes most of the polycyclic compounds,making them more soluble in aqueous solution. In a preferred process,the nanotube containing felts are refluxed in 2-5 M HNO₃ for 6-15 hoursat approximately 110°-125° C. Purified nanotubes may be filtered andwashed with 10 mM NaOH solution on a 3 micron pore size TSTP Isoporefilter. Next, the filtered nanotubes polished by stirring them for 30minutes at 60° C. in a S/N (Sulfuric acid/Nitric acid) solution. In apreferred embodiment, this is a 3:1 by volume mixture of concentratedsulfuric acid and nitric acid. This step removes essentially all theremaining material from the tubes that is produced during the nitricacid treatment.

[0103] Once the polishing is complete a four-fold dilution in water ismade and the nanotubes are again filtered on the 3 micron pore size TSTPIsopore filter. and the nanotubes are again washed with a 10 mM NaOHsolution. Finally, the nanotubes are stored in water, because drying thenanotubes makes it difficult to resuspend them.

[0104] The conditions may be further optimized for particular uses, butthis basic approach by refluxing in oxidizing acid has been shown to besuccessful. Purification according to this method will producesingle-wall nanotubes for use as catalysts, as components in compositematerials, or as a starting material in the production of tubular carbonmolecules and continuous macroscopic carbon fiber of single-wallnanotube molecules.

[0105] Single-Wall Carbon Nanotube Molecules

[0106] Single-wall carbon nanotubes produced by prior methods are solong and tangled that it is very difficult to purify them, or manipulatethem. However, the present invention provides for cutting then intoshort-enough lengths that they are no longer tangled and annealing theopen ends dosed. The short, closed tubular carbon molecules may bepurified and sorted very readily using techniques that are similar tothose used to sort DNA or size polymers. Thus, this inventioneffectively provides a whole new class of tubular carbon molecules.

[0107] Preparation of homogeneous populations of short carbon nanotubemolecules may be accomplished by cutting and annealing (reclosing) thenanotube pieces followed by fractionation. The cutting and annealingprocesses may be carried out on a purified nanotube bucky paper, onfelts prior to purification of nanotubes or on any material thatcontains single-wall nanotubes. When the cutting and annealing processis performed on felts, it is preferably followed by oxidativepurification, and optionally saponification, to remove amorphous carbon.Preferably, the starting material for the cutting process is purifiedsingle-wall nanotubes, substantially free of other material

[0108] The short nanotube pieces can be cut to a length or selected froma range of lengths, that facilitates their intended use. Forapplications involving the individual tubular molecules per se (e.g.,derivatives, nanoscale conductors in quantum devices, i.e., molecularwire), the length can be from just greater than the diameter of the tubeup to about 1,000 times the diameter of the tube. Typical tubularmolecules will be in the range of from about 5 to 1,000 nanometers orlonger. For making template arrays useful in growing carbon fibers ofSWNT as described below, lengths of from about 50 to 500 nm arepreferred.

[0109] Any method of cutting the achieves the desired length of nanotubemolecules without substantially affecting the structure of the remainingpieces can be employed. The preferred cutting method employs irradiationwith high mass ions. In this method, a sample is subjected to a fast ionbeam, e.g., from a cyclotron, at energies of from about 0.1 to 10giga-electron volts. Suitable high mass ions include those over about150 AMU's such as bismuth, gold, uranium and the like.

[0110] Preferably, populations of individual single-wall nanotubemolecules having homogeneous length are prepared starting with aheterogeneous bucky paper and cutting the nanotubes in the paper using agold (Au⁺³³) fast ion beam. In a typical procedure, the bucky paper(about 100 micron thick) is exposed to −10¹² fast ions per cm², whichproduces severely damaged nanotubes in the paper, on average every 100nanometers along the length of the nanotubes. The fast ions createdamage to the bucky paper in a manner analogous to shooting 10-100 nmdiameter “bullet holes” through the sample. The damaged nanotubes thencan be annealed (closed) by heat sealing of the tubes at the point whereion damage occurred, thus producing a multiplicity of shorter nanotubemolecules. At these flux levels, the shorter tubular molecules producedwill have a random distribution of cut sixes with a length peak nearabout 100 nm. Suitable annealing conditions are well known in thefullerene art, such as for example, baking the tubes in vaccum or inertgas at 1200° C. for 1 hour.

[0111] The SWNTs may also be cut into shorter tubular molecules byintentionally incorporating defect-producing atoms into the structure ofthe SWNT during production. These defects can be exploited chemically(e.g., oxidatively attacked) to cut the SWNT into smaller pieces. Forexample, incorporation of 1 boron atom for every 1000 carbon atoms inthe original carbon vapor source can produce SWNTs with built-in-weakspots for chemical attack.

[0112] Cutting may also be achieved by sonicating a suspension of SWNTsin a suitable medium such as liquid or molten hydrocarbons. One suchpreferred liquid is 1,2-dichloroethane. Any apparatus that producessuitable acoustic energy can be employed. One such apparatus is theCompact Cleaner (One Pint) manufactured by Cole-Parmer, Inc. This modeloperates at 40 KHz and has an output of 20 W. The sonication cuttingprocess should be continued at a sufficient energy input and for asufficient rime to substantially reduce the lengths of tubes, ropes orcables present in the original suspension. Typically times of from about10 minutes to about 24 hours can be employed depending on the nature ofthe starting material and degree of length reduction sought.

[0113] In another embodiment, sonication may be used to create defectsalong the rope lengths,,either by the high temperatures and pressurescreated in bubble colapse (−5000° C. and −1000 atm), or by the attack offree radicals produced by sonochemistry. These defects are attacked byS/N to cleanly cut the nanotube, exposing the tubes underneath for moredamage and cutting. As the acid attacks the tube the tube is completelycut open and slowly etches back its open end being unable to reclose atthe moderate temperature. In a preferred process, the nanotubes are bathsonocated while being stirred in 40-45° C. S/N for 24 hours Next, thenanotubes are stirred with no sonication in the S/N for 2 hours at40-45° C. This is to attack, with S/N, all the defects created by thesonication without creating more defects. Then the nanotubes are dilutedfour-fold with water, and then filtered using a 0.1 micron pore sizeVCTP filter. Next, the nanotubes are filtered and washed with a 10 mMNaOH solution on the VCTP filter. The nanotubes are polished by stirringthem for 30 minutes at 70° C. in a S/N solution. The polished nanotubesare diluted four-fold with water, filtered using the 0.1 micron poresize VCTP filters, then filtered and washed with 10 mM NaOH on a 0.1micron pore size VCTP filter, and then stored in water.

[0114] Oxidative etching e.g., with highly concentrated nitric acid, canalso be employed to effect cutting of SWNTs into shorter lengths. Forexample, refluxing SWNT material in concentrated HNO₃ for periods ofseveral hours to 1 or 2 days will result in significantly shorter SWNTs.The rate of cutting by this mechanism is dependent on the degree ofhelicity of the tubes. This fact may be utilized to facilitateseparation of tubes by type, i.e., (n,n) from (m,n).

[0115] Length distribution shortens systematically with exposure time tothe acid. For example, in a 3/1 concentrated sulfuric/nitric acid at 70°C. The average cut nanotube shortens at a rate of approximately 100 nmhr⁻¹. In a 4/1 sulfuric acid/30% aqueous hydrogen peroxide (“piranha”)mixture at 70° C., the shortening rate is approximately 200 nm hr⁻¹. Theetching rate is sensitive to the chrial index of the nanotubes (n,m),with all “arm-chair” tubes (m=x) having a distinct chemistry from the“zig-zag” tubes (m=0), and to a lesser extend with tubes of intermediatehelical angle (n=m).

[0116] The cleaned nanotube material may be cut into 50-500 nm lengths,preferably 100-300 nm lengths, by this process. The resulting pieces mayform a colloidal suspension in water when mixed with a surfactant suchas Triton X-100™ (Aldrich, Milwaukee, Wis.) These sable suspensionspermit a variety of manipulations such as sorting by length using fieldflow fractionation, and electrodeposition on graphite followed by AFMimaging.

[0117] In another embodiment, SWNTs can be cut using electron beamcutting apparatus in the known manner.

[0118] Combination of the foregoing cutting techniques can also beemployed.

[0119] Homogeneous populations of single-walled nanotubes may beprepared by fractionating heterogenous nanotube populations afterannealing. The annealed nanotubes may be disbursed in a aqueousdetergent solution or an organic solvent for the fractionation.Preferably the tubes will be disbursed by sonication in benzene,toluene, xylene or molten naphthalene. The primary function of thisprocedure is to separate nanotubes that are held together in the form ofropes or mats by van der Waals forces. Following separation inindividual nanotubes, the nanotubes may be fractionated by size by usingfractionation procedures which are well known, such as procedures forfractionating DNA or polymer fractionation procedures. Fractionationalso can be performed on tubes before annealing, particularly if theopen ends have substituents (carboxy, hydroxy, etc.), that facilitatethe fractionation either by size or by type. Alternatively, the closedtubes can be opened and derivatized to provide such substituents. Closedtubes can also be derivatized to facilitate fractionation, for example,by adding solubilizing moieties to the end caps.

[0120] Electrophoresis is one such technique well suited tofractionation of SWNT molecules since they can easily be negativelycharged. It is also possible to take advantage of the differentpolarization and electrical properties of SWNTs having differentstructure types (e.g., arm chair and zig-zag) to separate the nanotubesby type. Separation by type can also be facilitated by derivatizing themixture of molecules with a moiety that preferentially bonds to one typeof structure.

[0121] In a typical example, a 100 micron thick mat of black buckypaper, made of nanotubes purified by refluxing in nitric acid for 48hours was exposed for 100 minutes to a 2 GeV beam of gold (Au⁺³³) ionsin the Texas A&M Superconducting Cyclotron Facility (net flux of up to10¹² ions per cm²) The irradiated paper was baked in a vacuum at 1200°C. for 1 hr to seal off the tubes at the “bullet holes,” and thendispersed in toluene while sonicating. The resultant tubular moleculeswere examined via SEM, AFM and TEM.

[0122] The procedures described herein produce tubular molecules thatare single-wall nanotubes in which the cylindrical portion is formedfrom a substantially defect-free sheet of graphene (carbon in the formof attached hexagons) rolled up and joined at the two edges parallel toits long axis. The nanotube can have a fullerene cap (e.g., hemispheric)at one end of the cylinder and similar fullerene cap at the other end.One or both ends can also be open. Prepared as described herein, theseSWNT molecules are substantially free of amorphous carbon. Thesepurified nanotubes are effectively a whole new class of tubularmolecules.

[0123] In general the length, diameter and helicity of these moleculescan be controlled to any desired value. Preferred lenghts are up to 10₆hexagons; preferred diameters are about 5 to 50 hexagon circumference;and the preferred helical angle is 0° to 30°.

[0124] Preferably, the tubular molecules are produced by cutting andannealing nanotubes of predominately are-chair (n,n) configuration,which may be obtained by purifying material produced according to themethods discussed above. These (n,n) carbon molecules, purified asdescribed herein, are the first truly “metallic molecules.” Thesemolecules are useful for making electrical connectors for devices suchas integrated circuits or semiconductor chips used in computers becauseof the high electrical conductivity and small size of the carbonmolecule SWNT molecules are also useful as components of electricaldevices where quantum effects dominate at room temperatures, forexample, resonant tunneling diodes. The metallic carbon molecules areuseful as antennas at optical frequencies, and as probes for scanningprobe microscopy such as are used in scanning tunneling microscopes(STM) and atomic force microscopes (AFM). The semiconducting SWNTstructures, and (m, n) tube wherein m=n may be used, with appropriatedoping, as nanoscale semiconductor devices such as transistors.

[0125] the tubular carbon molecules of this invention may also be usedin RF shielding applications, e.g., to make microwave absorbingmaterials.

[0126] Single-walled nanotube molecules may serve as catalysts in any ofthe reactions known to be catalyzed as fullerenes, with the addedbenefits that the linear geometry of the molecule provides. The carbonnanotubes are also useful as supports for catalysts used in industrialand chemical processes such as hydrogenation, reforming and crackingcatalysts. Materials including the SWNT molecules can also be used ashydrogen storage devices in batters and fuel cell devices.

[0127] The tubular carbon molecules produced according to this inventioncan be chemically derivatized at their ends (which may be made eitheropen or closed with a hemi-fullerene dome). Derivatization at thefullerene cap structures is facilitated by the well-known reactivity ofthese structures. See, “The Chemistry of Fullerenes” R. Taylor ed., Vol.4 of the advanced Series in Fullerenes, World Scientific Publishers,Singapore, 1995, A. Hirsch, “The Chemistry of the Fullerenes, ” Thieme,1994. Alternatively, the fullerene caps of the single-walled nanotubesmay be removed at one or both ends of the tubes by short exposure tooxidizing conditions (e.g., with nitric acid or O₂/CO₂) sufficient toopen the tubes but not etch them back too far, and the resulting opentube ends maybe derivatized using known reaction schemes for thereactive sites at the graphene sheet edge.

[0128] In general, the structure of such molecules can be shown asfollows:

[0129] where

[0130] is a substantially defect-free cylindrical graphene sheet (whichoptionally can be doped with non-carbon atoms) having from about 10² toabout 10⁶ carbon atoms, and having a length of from about 5 to about1000 nm, preferably about 5 to about 500 nm,

[0131] is a fullerene cap that fits perfectly on the cylindricalgraphene sheet, has at least six pentagons and the remainder hexagonsand typically has at least about 30 carbon atoms;

[0132] n is a number from 0 to 30, preferably 0 to 12 and

[0133] R,R¹,R², R³, R⁴, and R⁵ each may be independently selected fromthe group consisting of hydrogen; alkyl, acyl, aryl, aralkyl, halogen;substituted or unsubstituted thiol; unsubstituted or substituted amino;hydroxy, and OR′ wherein R′ is selected from the group consisting ofhydrogen, alkyl, acyl, aryl, aralkyl, unsubstituted or substitutedamino;

[0134] substituted or unsubstituted thiol; and halogen; and a linear orcyclic carbon chain optionally interrupted with one or more heteroatom,and optionally substituted with one or more ═O, or ═S, hydroxy, anaminoalkyl group, an amino acid, or a peptide of 2-8 amino acids.

[0135] The following definitions are used herein.

[0136] The term “alkyl” as employed herein includes both straight andbranched chain radicals, for example methyl, ethyl, propyl, isopropyl,butyl, t-butyl, isobutyl, pentyl, hexyl, isohexyl, heptyl,4,4-dimethylpentyl, octyl, 2,2,4-trimethylpentyl, nonyl, decyl, undecyl,dodecyl, the various branched chain isomers thereof. The chain may belinear or cyclic saturated or unsaturated containing for example, doubleand triple bonds. The alkyl chain may be interrupted or substitutedwith, for example, one or more halogen, oxygen, hydroxyl, acceptablesubstitutes.

[0137] The term “acyl” as used herein refers to carbonyl groups of theformula —COR wherein R may be any suitable substituent such as, forexample, alkyl, aryl, aralkyl, halogen, substituted or unsubstitutedthiol; unsubstituted or substituted amino, unsubstituted or substitutedoxygen, hydroxy, or hydrogen.

[0138] The term “aryl” as employed herein refers to monocyclic, bicyclicor tricyclic aromatic groups containing from 6 to 14 carbons in the ringportion, such as phenyl, naphthyl, substituted phenyl, or substitutednaphthyl, wherein the substituent on either the phenyl or naphthyl maybe for example C₁₋₄ alkyl, halogen, C₁₋₄ alkoxy,hydroxy or nitro.

[0139] The term “aralkyl” as used herein refers to alkyl groups asdiscussed above having an aryl substitute, such as benzyl,p-nitrobenzyl, phenylethyl, diphenylmethyl, and triphenylmethyl.

[0140] The term “aromatic or non-aromatic ring” as used herein includes5-8 membered aromatic and non-aromatic rings uninterrupted orinterrupted with one or more heteroatom, for example O,S,SO, SO₂, and N,or the ring may be unsubstituted or substituted with, for example,halogen, alkyl, acyl, hydroxy, aryl, and amino, said heteroatom andsubstituent may also be substituted with, for example, alkyl, acyl,aryl, or aralkyl.

[0141] The term “linear or cyclic” when used herein includes, forexample, a linear chain which may optionally be interrupted by anaromatic or non-aromatic ring. Cyclic chain includes, for example, andaromatic or non-aromatic ring which may be connected to, for example, acarbon chain which either precedes or follows the ring.

[0142] The term “substituted amino” as used herein refers to an aminowhich may be substituted with one or more substituent, for example,alkyl, acyl, aryl, aralkyl, hydroxy, and hydrogen.

[0143] The term “substituted thiol” as used herein refers to a thiolwhich may be substituted with one or more substituent, for example,alkyl, acyl, aryl, aralkyl, hydroxy, and hydrogen.

[0144] Typically, open ends may contain up to about 20 substituents andclosed ends may contain up to about 30 substituents. It is preferred,dueto stearic hindrance, to employ up to about 12 substituents per end.

[0145] In addition to the above described external derivatization, theSWNT molecules of the present invention can be modified endohedrally,i.e., by including one or more metal atoms inside the structure, as isknown in the endohedral fullerene art. It is also possible to “load” theSWNT molecule with one or more smaller molecules that do not bond to thestructures, e.g., C₆₀, to permit molecular switching as the C₆₀ buckyball shuttles back and forth inside the SWNT molecule under theinfluence of external fields or forces.

[0146] To produce endohedral tubular carbon molecules, the internalspecies (e.g., metal atom, bucky ball molecules) can either beintroduced during the SWNT formation process or added after preparationof the tubular molecules. Incorporation of metals into the carbon sourcethat is evaporated to form the SWNT material is accomplished in themanner described in the prior art for making endohedralmetallofullerenes. Bucky balls, i.e., spheroidal fullerene molecules,are preferably loaded into the tubular carbon molecules of thisinvention by removing one or both ends caps of the tubes employingoxidation etching described above, and adding an excess of bucky ballmolecules (e.g., C₆₀, and C₇₀) by heating the mixture (e.g., from about500 to about 600° C.) in the presence of C₆₀, or C₇₀ containing vaporfor an equilibration period (e.g., from a few tenths of a percent up toabout 50 percent or more) of the tubes will capture a bucky ballmolecule during this treatment. By selecting the relative geometry ofthe tube and ball this process can be facilitated. For example, C₆₀ andC₇₀ fit very nicely in a tubular carbon molecule cut from a (10,10) SWNT(I.D.=1 nm). After the loading step, the tubes containing bucky ballmolecules can be closed (annealed shut) by heating under vaccum to about1100° C. Bucky ball encapsulation can be confirmed by microscopicexamination, e.g., by TEM.

[0147] Endohedrally loaded tubular carbon molecules can then beseparated from empty tubes and any remaining loading materials by takingadvantage of the new properties introduced into the loaded tubularmolecules, for example, where the metal atom imparts magnetic orparamagnetic properties to the tubes, or the bucky ball imparts extramass to the tubes. Separation and purification methods based on theseproperties and others will be readily apparent to those skilled in theart.

[0148] Fullerene molecules like C₆₀ or C₇₀ will remain inside theproperly selected tubular molecule (e.g., one based on (10,10) SWNTs)because from an electronic standpoint (e.g., by van der Waalsinteraction) the tube provides an environment with a more stable energyconfiguration than that available outside the tube.

[0149] Molecular Arrays of Single-Wall Carbon Nanotubes

[0150] An application of particular interest for a homogeneouspopulation of SWNT molecules is production of a substantiallytwo-dimensional array made up of single-walled nanotubes aggregating(e.g., by van der Waals forces) in substantially parallel orientation toform a monolayer extending in directions substantially perpendicular tothe orientation of the individual nanotubes. Such monolayer arrays canbe formed by conventional techniques employing “self-assembledmonolayers” (SAM) or Langmiur-Blodgett films see Hirch. pp. 75-76. Sucha molecular array is illustrated schematically in FIG. 4. In thisfigure, nanotubes 1 are bound to a substrate 2 having a reactive coating3 (e.g., gold).

[0151] Typically, SAMs are created on a substrate which can be a metal(such as gold, mercury or ITO(indium-tin-oxide)). The molecules ofinterest, here the SWNT molecules, are linked (usually covalently) tothe substrate through a linker moisty such as —S—,—S—(CH,)a—NH—₂—SiO₃(CH,)₃NH— or the like. The linker moiety may be bound first tothe substrate layer or first to the SWNT molecule (at an open or closedend) to provide for reactive self-assembly. Langmiur-Blodgett films areformed at the interface between two phase, e.g., a hydrocarbon (e.g.,benzene or toluene) and water. Orientation in the film is achieved byemploying molecule or linkers that have hydrophilic and lipophilicmoieties at opposite ends.

[0152] The configuration of the SWNT molecular array may be homogenousor heterogenous depending on the use to which it will be put. Using SWNTmolecules of the same type and structure provides a homogeneous array ofthe type shown in FIG. 4. By using different SWNT molecules, either arandom or ordered heterogeneous structure can be produced. An example ofan ordered heterogeneous array is shown in FIG. 5 where tubes 4 are(n,n), i.e., metallic in structure and tubes 5 are (m,n),i.e.,insulating. This configuration can be achieved by employing successivereactions after removal of previously masked areas of the reactivesubstrate.

[0153] Arrays containing from 10³ up to 10¹⁰ and more SWNT molecules insubstantially parallel relationships can be used per se as a nanoporousconductive. molecular membrane, e.g.,for use in batteries-such as thelithium ion battery This membrane can also be used (with or withoutattachment of a photoactive molecule such as cis-(bisthiacyanato bis(4,4′-dicarboxy-2,2′-bipyridine Ru (II)) to produce a highly efficientphoto cell of the type shown in U.S. Pat. No. 5,084,365.

[0154] One preferred use of the SWNT molecular arrays of the presentinvention is to provide a “seed” or template for growth of macroscopiccarbon fiber of single-wall carbon nanotubes as described below. The useof a macroscopic cross section in this template is particularly usefulfor keeping the live (open) end of the nanotubes exposed to feedstockduring growth of the fiber. The template array of this invention can beused as formed on the original substrate, cleaved from its originalsubstrate and used with no substrate (the van der Waals forces will holdit together) or erred to a second substrate more suitable for theconditions of fiber growth.

[0155] Where the SWNT molecular array is to be used as a seed ortemplate for growing macroscopic carbon fiber as described below, thearray need not be formed as a substantially two-dimensional array. Anyform of array that presents at its upper surface a two-dimensional arraycan be employed. In the preferred embodiment, the template moleculararray is a manipulatable length of macroscopic carbon fiber as producedbelow.

[0156] Another method for forming a suitable template molecular arrayinvolves employing purified buck paper as the starting material. Uponoxidative treatment of bucky paper surface (e.g., with O₂/CO₂ at about500° C.), the sides as well as ends of SWNTs are attacked and many tubeand/or rope ends protrude up from the surface of the paper. Disposingthe resulting bucky paper in an electric field (e.g., 100 V/cm² resultsin the protruding tubes and or ropes aligning in a directionsubstantially perpendicular to the paper surface. These tubes tend tocoalesce due to van der Waals forces to form a molecular array.

[0157] Alternatively, a molecular array of SWNTs can be made by“combining” the purified bucky paper starting material. “Combining”involves the use of a sharp microscopic tip such as the silicon pyramidon the cantilever of a scanning force microscope (“SFM”) to align thenanotubes. Specifically, combing is the process whereby the tip of anSFM is systematically dipped into, dragged through, and raised up from asection of bucky paper. An entire segment of bucky paper could becombed, for example, by (i) systematically dipping, dragging, raisingand moving forward an SFM tip along a section of the bucky paper, (ii)repeating the sequence in (i) until completion of a row; and (ii)repositioning the tip along another row and repeating (i) and (ii). In apreferred method of combing, the section of bucky paper of interest iscombed through as in steps (i)-(iii) above at a certain depth and thenthe entire process is repeated at another depth. For example, alithography script can be written and run which could draw twenty lineswith 0.5 μm spacing in a 10×10 μm square of bucky paper. The script canbe run seven times, changing the depth from zero to three μm in 0.5 μmincrements.

[0158] Large arrays (i.e., >10⁶ tubes) also can be assembled usingnanoprobes by combining smaller arrays or by folding linear collectionsof tubes and/or ropes,over (i.e., one folding of a collection of n tubesresults in a bundle with 2 n tubes).

[0159] Macroscopic arrays can also be formed by providing a nanoscalemicrowell structure a SiO₂ coated silicon wafer with >10⁶ rectangular 10nm wide, 10 nm deep wells formed in the surface by electron beamlithographic techniques). A suitable catalyst metal duster (orprecursor) is deposited in each well and a carbon-containing feedstockis directed towards the array under growth conditions described below toinitiate growth of SWNT fibers from the wells. Catalysts in the form ofpreformed nanoparticles (i.e., a few nanometers in diameter) as bed inDai et al., “Single-Wall Nanotubes Produced by Metal-CatalyzedDisproportionation of Carbon Monoxide,” Chem. Phys. Lett. 260 (1996),471-475 (“Dai”) can also be used in the wells. An electric field can beapplied to orient the fibers in a direction substantially perpendicularto the wafer surface.

[0160] Growth of Continuous Carbon Fiber from SWNT Molecular Arrays

[0161] The present invention provides methods for growing continuouscarbon fiber from SWNT molecular arrays to any desired length The carbonfiber which comprises an aggregation of substantially parallel carbonnanotubes may be produced according to this invention by growth(elongation) of a suitable seed molecular array. The preferred SWNTmolecular array is produced as described above from a SAM of SWNTmolecules of substantially uniform length. As used herein, the term“macroscopic carbon fiber” refers to fibers having a diameter largeenough to be physically manipulated, typically greater than about 1micron and preferably greater than about 10 microns.

[0162] The first step in the growth process is to open the growth end ofthe SWNTs in the molecular array. This can be accomplished as describedabove with an oxidative treatment. Next, a transition metal catalyst isadded to the open-ended seed array. This transition metal catalyst canbe any transition metal that will cause conversion of thecarbon-containing feedstock described below into highly mobile carbonradicals that can rearrange at the growing edge to the favored hexagonstructure. Suitable materials include transition metals, andparticularly the Group VI or VIII transition metals, i.e., chromium(Cr), molybdenum (Mo), tungsten (W), iron (Fe), cobalt (Co), nickel(NI), ruthenium (Ru), rhodium (Rh), palladium (Pd), osmium (Os), iridium(Ir) and platinum (Pt). Metals from the lanthanide and actinide seriesmay also be used. Preferred are Fe, Ni, Co and mixtures thereof. Mostpreferred is a 50/50 mixture (by weight) of Ni and Co.

[0163] The catalyst should be present on the open SWNT ends as a metalcluster containing from about 10 metal atoms up to about 200 metal atoms(depending on the SWNT molecule diameter). Typically, the reactionproceeds most efficiently if the catalyst metal cluster sits on top ofthe open tube and does not bridge over more than one or two tubes.Preferred are metal clusters having a cross-sectional equal to fromabout 0.5 to about 1.0 times the tube diameter (e.g., about 0.7 to 1.5nm).

[0164] In the preferred process, the catalyst is formed, in situ, on theopen tube ends of the molecular array by a vacuum deposition process.Any suitable equipment, such as that used in Molecular Beam Epitaxy(MBE) deposition, can be employed. One such device is a Kudsen EffusionSource Evaporator. It is also possible to effect sufficient depositionof metal by simply heating a wire in the vicinity of the tube ends(e.g., a Ni/CO wire or separate Ni and CO wires) to a temperature belowthe melting point at which enough atoms evaporate from one wire surface(e.g., from about 900 to about 1300° C.). The deposition is preferablycarried out in a vacuum with prior outgassing Vacuums of about 10⁻⁶ to10⁻⁸ Torr are suitable. The evaporation temperature should be highenough to evaporate the metal catalyst. Typically, temperatures in therange of 1500 to 2000° C. are suitable for the Ni/Co cast of thepreferred embodiment. In the evaporation process, the metal is typicallydeposited as monolayers of metal atoms. From about 1-10 monolayer willgenerally give the required amount of catalyst. The deposition oftransition metal clusters on the open tube tops can also be accomplishedby laser vaporization of metal targets in a catalyst deposition zone.

[0165] The actual catalyst metal cluster formation at the open tube endsis carried out by heating the tube ends to a throw high enough toprovide sufficient species mobility to permit the metal atoms to findthe open ends and assemble into clusters, but not so high as to effectclosure of the tube ends. Typically, temperatures of up to about 500° C.are suitable. Temperatures in the range of about 400-500° C. arepreferred for the Ni/Co catalyts system of one preferred embodiment.

[0166] In a preferred embodiment, the catalyst metal cluster isdeposited on the open nanotube end by a docking process that insuresoptimum location for the subsequent growth reaction. In this process,the metal atoms are supplied as described above, but the conditions aremodified to provide reductive conditions, e.g., at 800° C., 10 millitorrof H₂ for I to 10 minutes. There conditions cause the metal atomclusters to migrate through the system in search of a reactive site.During the reductive heating the catalyst material will ultimately findand settle on the open tube ends and begin to etch back the tube. Thereduction period should be long enough for the catalyst particles tofind and begin to etch back the nanotubes, but not so long as tosubstantially etch away the tubes. By changing to the above-describedgrowth conditions, the etch-back process is reversed. At this point, thecatalyst particles are optimally located with respect to the tube endssince they already were catalytically active at those sites (albeit inthe reverse process).

[0167] The catalyst can also be supplied in the form of catalystprecursors which convert to active form under growth conditions such asoxides, other salts or ligand stabilized metal complexes. As an example,transition metal complexes with alkylamines (primary, secondary ortertiary) can be employed. Similar alkylamine complexes of transitionmetal oxides also can be employed.

[0168] In an alternative embodiment, the catalyst may be supplied aspreformed nanoparticles (i.e., a few nanometers in diameter) asdescribed in Dai.

[0169] In the next step of the process of the present invention, theSWNT molecular array with catalyst deposited on the open tube ends issubjected to tube growth (extension) conditions. This may be in the sameapparatus in which the catalyst is deposited or a different apparatus.The apparatus for carrying out this process will require, at a minimum,a source of carbon-containing feedstock and a means for maintaining thegrowing end of the continuous fiber at a growth and annealingtemperature where carbon from the vapor can be added to the growing endsof the individual nanotubes under the direction of the transition metalcatalyst. Typically, the apparatus will also have means for continuouslycollecting the carbon fiber. The process will be described forillustration purposes with reference to the apparatus shown in FIGS. 6and 7.

[0170] The carbon supply necessary to grow the SWNT molecular array intocontinuous fiber is supplied to the reactor 10, in gaseous form throughinlet 11. The gas stream should be directed towards the front surface ofthe growing array 12. The gaseous carbon-containing feedstock can be anyhydrocarbon or mixture of hydrocarbons including alkyls, acyls, aryls,aralkyls and the like, as defined above. Preferred are hydrocarbonshaving from about 1 to 7 carbon atoms. Particularly preferred aremethane, ethane, ethylene, actylene, acetone, propane, propylene and thelike. Most preferred is ethylene. Carbon monoxide may also be used andin some reactions is preferred. Use of CO feedstock with preformedMo-based nano-catalysts is believed to follow a different reactionmechanism than that proposed for in situ-formed catalyst clusters. SeeDai.

[0171] The feedstock concentrations is preferably as chosen to maximizethe rate of reaction, with higher concentrations of hydrocarbon givingfaster growth rates. In general, the partial pressure of the feedstockmaterial (eg, ethylene) can be in the 0.001 to 1000.0 Torr range, withvalues in the range of about 1.0 to 10 Torr being preferred. The growthrate is also a function of the,temperature of the growing array tip asdescribed below, and as a result growth temperatures and feed stockconcentration can be balanced to provide the desired growth rates.

[0172] It is not necessary or preferred to preheat the carbon feedstockgas, since unwanted pyrolysis at the reactor walls can be minimizethereby. The only heat supplied for the growth reaction should befocused at the growing tip of the fiber 12. The rest of the fiber andthe reaction apparatus can be kept at room temperature. Heat can besupplied in a localized fashion by any suitable means. For small fibers(<1 mm in diameter), a laser 13 focused at the growing end is preferred(e.g., a C-W laser such as an argon ion laser beam at 514 nm). Forlarger fibers, heat can be supplied by microwave energy or R-F energy,again localized at the growing fiber tip. Any other form of concentratedelectromagnetic energy that can be focused on the growing tip can beemployed (e.g., solar energy). Care should be taken, however, to avoidelectromagnetic radiation that will be absorbed to any appreciableextent by the feed stock gas.

[0173] The SWNT molecular array tip should be heated to a temperaturesufficient to cause growth and efficient annealing of defects in thegrowing fiber, thus forming a growth and annealing zone at the tip. Ingeneral, the upper limit of this temperature is governed by the need toavoid pyrolysis of the feedstock and fouling of the reactor orevaporation of the deposited metal catalyst. For most feedstocks this isbelow about 1300° C. The lower end of the acceptable temperature rangeis typically about 500° C., depending on the feedstock and catalystefficiency. Preferred are temperatures in the range of about 500° C. toabout 30 1200° C. More preferred are temperatures in the range of fromabout 700° C. to about 1200° C. Temperatures in the range of about 900°C. to about 1100° C. are the most preferred, since at these temperaturesthe best annealing of defects occurs. The temperature at the growing endof the cable is preferably monitored by, and controlled in response to,an optical pyrometer 14, which measures the incandescence produced.While not preferred due to potential fouling problems, it is possibleunder some circumstances to employ an inert sweep gas such as argon orhelium.

[0174] In general, pressure in the growth can be in the range of 1millitorr to about 1 atmosphere. The total pressure should be kept at 1to 2 times the partial of the carbon feedstock. A vaccum pump 15 may beprovided as shown. It may be desirable to recycle the feedstock mixtureto the growth chamber. As the fiber grows it can be withdrawn from thegrowth chamber 16 by a suitable transport mechanism such as drive roll17 and idler roll 18. The growth chamber 16 is in direct communicationwith a vacuum feed lock zone 19.

[0175] The pressure in the growth chamber can be brought up toatmospheric, if necessary, in the vacuum feed lock by using a series ofchambers 20. Each of these chambers is separated by a loose TEFLONO-ring seal 21 surrounding the moving fiber. Pumps 22 effect thedifferential pressure equalization. A take-up roll 23 continuouslycollects the room temperature carbon fiber cable. Product output of thisprocess can be in the range of 10⁻³³ to 10¹ feet per minute or more. Bythis process, it is possible to produce tons per day of continuouscarbon fiber made up of SWNT molecules.

[0176] Growth of the fiber can be terminated at any stage (either tofacilitate manufacture of a fiber of a particular length or when toomany defects occur). To restart growth, the end may be cleaned (e.g.,reopened) by oxidative etching (chemically or electrochemically). Thecatalyst particles can then be reformed on the open tube ends, andgrowth continued.

[0177] The molecular array (template) may be removed from the fiberbefore or after growth by macroscopic physical separation means, forexample by cutting the fiber with scissors to the desired length. Anysection from the fiber may be used as the template to initiateproduction of similar fibers.

[0178] The continuous carbon fiber of the present invention can also begrown from more than one separately prepared molecular array ortemplate. The multiple arrays can be the same or different with respectto the SWNT type or geometric arrangement in the array. Large cable-likestructures with enhanced tensile properties can he grown from a numberof smaller separate arrays as shown in FIG.8. In addition to the maskingand coating techniques described above, it is possible to prepare acomposite structure, for example, by surrounding a central core array ofmetallic SWNTs with a series of smaller circular non-metallic SWNTarrays arranged in a ring around the core array as shown in FIG. 9.

[0179] Not all the structures contemplated by this invention need beround or even symmetrical in two-dimensional cross section, It is evenpossible to align multiple molecular array seed templates in a manner asto induce nonparallel growth of SWNTs in some portions of the compositefiber, thus producing a twisted, helical rope, for ample It is alsopossible to catalytically grow macroscopic carbon fiber in the presenceof an electric field to aid in alignment of the SWNTs in the fibers, asdescribed above in connection with the formation of template arrays.

[0180] Random Growth of Carbon Fibers From SWNTs

[0181] While he continuous growth of ordered bundles of SWNTs describedabove is desirable for many applications, it is also possible to produceuseful compositions comprising a randomly oriented mass of SWNTs, whichcan include individual tubes ropes and/or cables. The random growthprocess has the ability to produce large quantities, i.e., tons per day,of SWNT material.

[0182] In general the random growth method comprises providing aplurality of SWNT seed molecules that are supplied with a suitabletransition metal catalyst as described above, and subjecting the seedmolecules to SWNT growth conditions that result in elongation of theseed molecule by several orders of magnitude, e.g., 10² to 10¹⁰ or moretimes its original length

[0183] The seed SWNT molecules can be produced as described above,preferably in relatively short lengths, e.g., by cutting a continuousfiber or purified bucky paper. In a preferred embodiment, the seedmolecules can be obtained after one initial run on the SWNT feltproduced by this random growth process (e.g., by cutting). The lengthsdo not need to be uniform and generally can range from about 5nm to 10μm in length.

[0184] These SWNT seed molecules may be formed on macroscale ornanoscale supports that do not participate in the growth reaction. Inanother embodiment, SWNTs or SWNT structures can be employed as thesupport material/seed. For example, the self assembling techniquesdescribed below can be used to form a three-dimensional SWNTnanostructure. Nanoscale powders produced by these technique have theadvantage that the support material can participate in the random growthprocess.

[0185] The supported or unsupported SWNT seed materials can be combinedwith a suitable growth cat as described above, by opening SWNT moleculeends and depositing a metal atom cluster. Alternatively, the growthcatalyst can be provided to the open end or ends of the seed moleculesby evaporating a suspension of the seeds in a suitable liquid containinga soluble or suspended catalyst precursor For example, when the liquidis water, soluble metal salts such as Fe (NO₃)₃, Ni (NO₃)₂ or CO (NO₃)₂and the like may be employed as catalyst precursors. In order to insurethat the catalyst material is properly positioned on the open end(s) ofthe SWNT seed molecules, it may be necessary in some circumstances toderivitize the SWNT ends with a moiety that binds the catalystnanoparticle or more preferably a ligand-stabilized catalystnanoparticle.

[0186] In the first step of the random process the suspension of seedparticles containing attached catalysts or associated with dissolvedcatalyst precursors is injected into an evaporation zone where themixture contacts a sweep gas flow and is heated to a temperature in therange of 250-500° C. to flash evaporate the liquid and provide anentrained reactive nanoparticle (i.e., seed/cyst). Optionally thisentrained particle stream is subjected to a reduction step to furtheractivate the catalyst (e.g., heating from 300-500° C. in H₂). Acarbonaceous feedstock gas of the type employed in the continuous growthmethod described above, is then introduced into the sweep gas/activenanoparticle stream and the mixture is carried by the sweep gas into andthrough a growth zone.

[0187] The reaction conditions for the growth zone are as describedabove, i.e., 500-1000° C. and a total pressure of about one atmosphere.The partial pressure of the feedstock gas (e.g., ethylene, CO) can be inthe range of about 1 to 100 Torr. The reaction is preferably carried outin a tubular reactor through which a sweep gas (e.g., argon) flows.

[0188] The growth zone may be maintained at the appropriate growthtemperature by 1) preheating the feedstock gas, 2) preheating the sweepgas, 3) externally heating the growth zone, 4) applying localizedheating in the growth zone, e.g., by laser or induction coil, or anycombination of the foregoing.

[0189] Downstream recovery of the product produced by this process canbe effected by known means such as filtration centrifugation and thelike. Purification may be accomplished as described above. Felts made bythis random growth process can be used to make composites, e.g. withpolymers, epoxies, metals, carbon (i.e., carbon/carbon materials) andhigh T superconductors for flux pinning.

[0190] Macroscopic Carbon Fiber

[0191] The macroscopic carbon fiber produced as described herein is madeup of an aggregate of large number of single-wall nanotubes preferablyin generally parallel orientation. While individual nanotubes maydeviate from parallel orientation relative to any other individualnanotube, particularly for very short distances, over macroscopicdistances the average orientation of all of the nanotubes preferablywill be generally parallel to that of all other nanotubes in theassembly (macroscopic distances as described herein are generallyconsidered to be greater than 1 micron). In one preferred form, theSWNTs will be arranged in a regular triangular lattice, i.e., in aclosest packing relationship.

[0192] The carbon fiber of this invention is made up of individualtubular molecules and may be in whole or in part either crystalline oramorphous in structure. The degree of order in the fiber will dependboth on the geometric relationship of the tubes in the molecular arrayand the growth and annealing conditions. The fiber may be subjected toorientation or other post-formation treatments before or aftercollection. The fiber produced by this process may, for example, befurther spun or braided into larger yarns or cables. It is alsocontemplated that as produced fiber will be large enough in diameter formany applications.

[0193] Generally the macroscopic carbon fiber produced according to thisinvention consists of a sufficient number of substantially parallelsingle-wall nanotubes that it is large enough in diameter to bepractically handled as an individual fiber and/or processed into largercontinuous products. The macroscopic nature of the assembly of nanotubesis also important for end uses such as transmission of electric currentover these nanotube cables. A macroscopic carbon fiber according to thisinvention preferably will contain at least 10⁶ single-wall carbonnanotubes, and more preferably at least 10⁹ single-wall carbonnanotubes. The number of assembled nanotubes is vastly larger than thenumber (<10³) that spontaneously align during the formation ofsingle-wall nanotube ropes in the condensing carbon vapor of a carbonarc or laser vaporization apparatus. For many applications the preferreddiameter of the macroscopic carbon fiber of this invention will be inthe range of from about 1 to about 10 microns. Some applications, e.g.,power transmission cables, may require fiber diameters of up to a fewcentimeters. It is also possible to include dopants, e.g., metals,halogens, FeCl₃ and the like, physically entrapped between the tubes ofthe fiber.

[0194] The macroscopic carbon fiber of this invention will generally beat least 1 millimeter in length, with the exact length depending uponthe particular application for which the fiber is used. For example,where the fiber is designed to substitute for conventional graphitecarbon fiber for reinforcing the length of the fiber according to thisinvention will be similar to the length of the convention carbon fibers.Where the macroscopic carbon fiber according to this invention is usedfor electrical conductance, the length of the fiber preferablycorresponds to the distance over which electrical conductance isdesired. Typically such distances may be from 1-100 microns or up to1-10 millimeters or greater. Where conductance over macroscopicdistances is desired, it is preferred that the macroscopic carbon fiberaccording to this invention have a length on the order of meters orgreater.

[0195] One reason the continuous carbon fiber of the present inventionhas such improved physical properties is its structure as a high orderlaminate-as many as 10⁹ or more individual tubular molecules arelaminated together. This structure provides much higher strength inbending, significantly higher resistance to failure by chemicalcorrosion, better wear, more elasticity and a completely differenttensile failure mechanism from similar monolithic materials. Thesingle-wall carbon nanotube fiber of this invention provides extremelyhigh tensile strength at low weight (˜100 times stronger than steelwhile having only one sixth the weight). This fiber has an electricalconductivity similar to copper. In addition the thermal conductivityalong the fiber is approximately that of diamond. The carbon fiber ofthis invention also has high chemical resistance (better than spheroidalfullerenes such as C^(α)C⁷⁰). In general the substantially defect-freecontinuous carbon fiber of this invention will exhibit improvedproperties over conventional carbon fibers because of its near perfectmulti-hexagonal structure that extends over macroscopic distances.

[0196] In a particular embodiment, macroscopic carbon fiber according tothis invention is grown from a molecular array comprising a SAM having aregion substantially comprising single-wall nanotubes in armchairorientation, the region having a diameter of at least one micron andpreferably at least 100 microns. By use of masks on the surface uponwhich the monolayer is assembled, the area containing single-wallednanotubes in armchair structure is completely surrounded on all sides bya concentric region of tubes having a chiral or zig-zag structure.Elongation from this template will produce a conducting core surroundedby a semi-conducting or insulating sheath, each layer made up of singlemolecules of essentially infinite length. In a similar manner, aco-axial transmission cable with several layers can be produced.

[0197] Applications of these carbon fibers include all those currentlyavailable for graphite fibers and high strength fibers such as membranesfor batteries and fuel cells; chemical filters; catalysts supports;hydrogen storage (both as an absorbent material and for use infabricating high pressure vessels); lithium ion batteries; and capacitormembranes. These fibers can also be used in electromechanical devicessuch as nanostrain gauges (sensitive to either nanotube bend or twist)Fibers of this invention can be used as product or spun into threads orformed into yarns or to fibers using known textile techniques.

[0198] The carbon fiber technology of this invention also facilitates aclass of novel composites employing the hexaboronitride lattice. Thismaterial forms graphene-like sheets with the hexagons made of B and Natoms (e.g., B₃ N₂ or C₂ BN₃). It is possible to provide an outercoating to a growing carbon fiber by supplying a BN precursor (e.g.,tri-chloroborazine, a mixture of NH₃ and BCl₃ or diborane) to the fiberwhich serves as a mandrel for the deposition of BN sheets. This outer BNlayer can provide enhanced insulating properties to the metallic carbonfiber of the present invention. Outer layers of pyrolytic carbonpolymers or polymer blends may also be employed to impart. By changingthe feedstock in the above described process of this invention from ahydrocarbon to a BN precursor and back again it is possible to grow afiber made up of individual tubes that alternate between regions of allcarbon lattice and regions of BN lattice. In another embodiment of thisinvention, an all BN fiber can be grown by starting with a SWNT templatearray topped with a suitable catalyst and fed BN precursors. Thesegraphene and BN Systems can be mixed because of the very close match ofsize to the two hexagonal units of structure In addition, they exhibitenhanced properties due to the close match of coefficients of thermalexpansion and tensile properties. BN fibers can be used in composites asreinforcing and strengthening agents and many of the other usesdescribed above for carbon fibers.

[0199] Device Technology Enabled by Products of this Invention

[0200] The unique properties of the tubular carbon molecules, moleculararrays and macroscopic carbon fibers of the present invention provideexciting new device fabrication opportunities.

[0201] 1. Power Transmission Cable

[0202] Current power transmission-line designs generally employ aluminumconductors, often with steel strand cores for strength (i.e., theso-called ASCR conductor). The conductors have larger losses than copperconductors and generally are not shielded leading to corona dischargeproblem. The continuous carbon fibers made form large (>10⁶)aggregations of SWNTs can be used to fabricate power transmission cablesof unique designs and properties. One such design is shown in FIG. 10.This design is essentially a shielded coaxial cable capable of EHV(extra high voltage) power transmission, (i.e., >500 KV and preferablyover 10⁶V) and having heretofore unattainable strength-to-weightproperties and little or no corona discharge problems.

[0203] The illustrated design, which exemplifies the use of the SWNTbased carbon fiber conductors produced as described above (e.g., fromn,n metallic SWNTs), consists of a central conductor 30 and a coaxialouter conductor 31, separated by an insulating layer 32. The centralconductor carries the power transmission which the outer layer conductoris biased to ground. The central conductor can be a solid metalliccarbon fiber. Alternatively, the central conductor can comprise a bundleof metallic carbon fiber strands which may be aggregated helically as iscommon in ACSR conductors.

[0204] The inner conductor can also comprise an annular tube surroundingan open core space in which the tube is a woven or braided fabric madefrom metallic carbon fibers as described above. The insulating layer canbe any light weight insulating material. Among the preferred embodimentsare strands or woven layers of BN fibers made as described above and theuse of an annular air space (formed using insulating spacers).

[0205] The, outer conductor layer is also preferably made from hexicallywound strands of metallic carbon fiber as described above. This groundedlayer essentially eliminates corona discharge problems or the need totake conventional steps to reduce these emissions.

[0206] The resulting coaxial structure possesses extremely highstrength-to-weight properties and can be used to transmit greater thanconventional power levels over greater distances with lower losses.

[0207] One of the above described power cable assemblies can be used toreplace each of the conductors used for separate phases in theconventional power transmission system. It is also possible byfabricating a multilayer annular cable with alternating metallic carbonfiber conductors and insulating layers to provide a single powertransmission-cable carrying three or more phases, thus greatlysimplifying the installation and maintenance of power lines.

[0208] 2. Solar Cell

[0209] A Gratzel cell of the type described in U.S. Pat. No. 5,084,365(incorporated herein by reference in its entirety) can be fabricatedwith the nanocrystalline TiO₂ replaced by a monolayer molecular array ofshort carbon nanotube molecules as described above. The photoactive dyeneed not be employed since the light striking the tubes will beconverted into an oscillating electronic current which travels along thetube length. The ability to provide a large charge separation (thelength of the tubes in the array) creates a highly efficient cell It isalso contemplated by the present invention to use a photoactive dye(such as cis-[bisthiacyanato bis (4,4′-dicarboxy-2-2′-bipyridine Ru(II))]attached to the end or each nanotube in the array to furtherenhance the efficiency of the cell. In another embodiment of the presentinvention, the TiO₂ nanostructure described by Gratzel can serve as anunderlying support for assembling an array of SWNT molecules. In thisembodiment, SWNTs are attached directly to the TiO₂ (by absorptiveforces) of first derivatized to provide a linking moiety and then boundto the TiO₂ surface. This structure can be used with or without aphotoactive dye as described above.

[0210] 3. Memory Device

[0211] The endohedrally loaded tubular carbon molecule described abovecan be used to form the bit structure in a nanoscale bistablenon-volatile memory device. In one form this bit structure comprises aclosed tubular carbon molecule with an enclosed molecular entity thatcan be caused to move back and forth in the tube under the influences ofexternal control. It is also possible to fill a short nanotube moleculewith magnetic nanoparticles,(e.g., Ni/CO) to form a nanobit useful inmagnetic memory devices.

[0212] One preferred form of a bit structure is shown in FIG. 11. Thetubular carbon molecule 40 this bit should be one exhibits a good fitmechanically with the movable internal moiety 41, i.e., not too small toimpede its motion. The movable internal moiety should be chosen (1) tofacilitate the read/write system employed with the bit and (2) tocompliment the electronic structure of the tube.

[0213] One preferred arrangement of such a nanobit employs a shortclosed tubular carbon molecule (e.g., about 10-50 nm long) made from a(10,10) SWNT by the above-described process, and containing encapsulatedtherein a C₆₀ or C₇₀ spherodial fullerene molecule. Optionally the C₆₀or C₇₀ molecule (bucky ball) can be endohedrally or exohedrally doped.The C₆₀ bucky ball is almost a perfect fit in a (10,10) tube. Moreimportantly, the electronic environment inside the tube is highcompatible with that of the bucky ball, particularly at each end, sincehere the inner curvature of the (10,10) tube at the end cap matches theouter curvature of the bucky ball. This configuration results in optimumvan der Waals interaction As shown in FIG. 12 the energy thresholdrequired to get one bucky ball out of the end cap (where it is in themost electronically stable configuration) serves to render the bitbistable.

[0214] One preferred read/write structure for use with the memory bitdescribed above is shown in FIG. 11. Writing to the bit is accomplishedby applying a polarized voltage pulse through a nanocircuit element 42(preferably a SWNT molecule). A positive pulse will pull the bucky balland a negative pulse will push the bucky ball. The bistable nature ofthe bit will result in the bucky ball staying in this end of the tubewhen the pulse is removed since that is where the energy is lowest. Toread the bit, another nanocircuit element 43 (again preferable, a SWNTmolecule) is biased with a V_(READ) If the bucky ball is present in thedetection end, it supplies the necessary levels for current toresonantly tunnel across the junction to the ground voltage 44 (in afashion analogous to a resonant tunneling diode) resulting in a firststable state being read If the bucky ball is not present in thedetection end, the energy levels are shifted out of resonance and thecurrent does not tunnel across the junction and a second stable state isread. Other forms of read/write structure (e.g., microactuators) can beemployed as will be recognized by one skilled in the art.

[0215] A memory device can be constructed using either a two-orthree-dimensional array of the elements shown in FIG. 12. Because theelements of the memory array are so small (e.g., ˜5 nm ×25 nm),extremely high bit densities can be achieved, i.e. >1.0 terabit/cm²(i.e., a bit separation of 7.5 nm). Because the bucky ball only has tomove a few nanometers and its mass is so small, the write time of thedescribed device is on the order of 10¹⁰ seconds.

[0216] 4. Lithium Ion Battery

[0217] The present invention also relates to a lithium ion secondarybattery in which the anode material includes a molecular ray of SWNTsmade as described above (e.g., by SAM techniques). The anode materialcan comprise a large number (e.g., >10³) short nanotube molecules boundto a substrate. Alternatively, the end of a macroscopic carbon fiber asdescribed above can serve as the microporous anode surface.

[0218] The tubular carbon molecules in this array may be open or closed.In either case, each tubular carbon molecule provides a structurallystable microporosity for the intercalation of lithium ions, i.e., intothe open tubes or into triangular pores of an end cap. The resultingfullerene intercalation compound (FIC) can be used, for example, with anaprotic organic electrolyte containing lithium ions and a LiCoO₂ cathodeto form an improved lithium ion secondary battery of the type describedin Nishi, “The Development of Lithium Ion Secondary Batteries,” 1996IEEE symposium on VLSI Circuits and shown in FIG. 13. In this figure,the anode 50 comprises a large number of SWNTs 51 in an orderedmolecular array. Cathode 52, electro 53, lithium ions 54 and electrons55 make up the remaining elements of the cell.

[0219] The use of the molecular array FICs of this invention provides alithium-storing medium that has a high charge capacity (i.e., >600 mAh/g) which is stable during charging and possesses excellent cylability,and that results in an improved safe rechargeable battery.

[0220] The anode is characterized by high current, high capacity, lowresistance, highly reversible and is nano-engineered from carbon withmolecular perfection. The anode is constructed as a membrane of metallicfullerene nanotubes arrayed as a bed-of-nails, the lithium atoms beingstored in the spaces either between the adjacent tubes or down thehollow pore within each tube. Chemical derivatization of the open endsof the tubes will then be optimized to produce the best possibleinterface with the electrolyte. The derivative is preferably an organicmoiety which provides a stable interface where the redox reaction canoccur. In general, the organic moiety should be similar in structure tothe electrolyte. One preferred derivitizing agent is polyethylene oxideand, in particular, polyethylene oxide oligomers.

[0221] The electrochemistry of the nano-engineered nanotube membranesare used for electrode applications. Important aspects are to derivatizetheir ends and sides in such a way as to provide an optimal interfacefor a lithium-ion battery electrolyte. This will result in a batterelectrode that is highly accessible to the lithium ions, thereforecapable of delivering high power density, and equally important,overcomes the ubiquitous SEl (solid-electrolyte interface) problem thatsignificantly reduces electrode capacity and reversibility.

[0222] Li⁺ is the ion choice for rechargeable batteries. Bested only bythe proton as a lightweight counter-ion, Li profits from theavailability of a wide class of solid and liquid electrolytes as a largechoice of cathode materials, primarily metal oxides with 3D networks ofintercalation sites in which the Li⁺ resides in the discharged state.The first rechargeable Li batteries used metallic Li as an anode, butseveral drawbacks existed:

[0223] loss of Li due to dendrite growth during recharging;

[0224] safety problems associated with the reactivity of Li metal in thepresence of organic solvents; and

[0225] the potential for anode-cathode shorts through the separator dueto the aforementioned Li dendrites.

[0226] A solution to the safety problems was found by replacing Li metalby a Li carbon intercalation anode, giving birth to the “rocking chair”battery in which the Li is never reduced to Li⁰ and Li⁺ shuttles betweenintercalation sites in the carbon anode and metal cathode as the batteryis charged and discharged respectively. Graphite was used in the firstgeneration Li-ion batteries, largely because the solid state chemistryof Li-graphite was well understood. Happily, the potential of Li⁺ ingraphite is within a few tens of MV of the potential of Li⁰, so the useof graphite in place of Li metal imposes a small weight and volumepenalty but no significant penalty in cell voltage.

[0227] But the use of graphite brought its own problems to thetechnology.

[0228] the best electrolytes (e.g., LiClO₄ dissolved in propylenecarbonate) which have good Li⁺ conductivity at ambient T alsoco-intercalate by solvating the Li⁺, leaving to exfoliation of thegraphite, dimensional instabilities and premature failure, and

[0229] The diffusivity of Li⁺ in graphite is rather low at ambient T,controlled by the large barrier for jump diffusion (commensuratelattice) between adjacent hexagonal interstitial sites in the graphitelattice.

[0230] The first problem was overcome by the development of newelectrolytes which did not co-intercalate, e.g., LiPF₆ in a mixture ofdimethyl carbonate and ethylene carbonate, which however had adetrimental effect on the electrolyte contribution to ion transportkinetics. The second problem required the use of finely divided graphite(powder, chopped fibers, foams) which in turn increased the surface areasubstantially, leading inexorably to yet a new set of problems, namelycapacity fade due to the formation of surface film (SEI:“solid-electrolyte interface”) during the first anode intercalation halfcycle. This in turn required assembling the battery with extraLi-containing cathode material to provide for the Li consumed by SEIformation, thus reducing the capacity. Not much is known about the SEI,but it is widely agreed that the carbonates (from electrolytedecomposition) are an important constituent. A widely accepted criterionin industry is that capacity loss due to SEI formation should not exceed10% of the available Li.

[0231] Subsequent research explored the use of her forms of(nano-crystalline) carbon: carbon black, pyrolyzed coal and petroleumpitches and polymers, pyrolyzed natural products (sugars, nutshells,etc.), “alloys” of carbon with other elements (boron, silicon, oxygen,hydrogen), and entirely new systems such as tin oxides. Some of theseexhibit much larger Li capacities than graphite, but the microscopicorigins of this “excess capacity” are largely unknown. In general thecycling behavior of these materials is much worse than graphite, and thehydrogen-containing materials also exhibit large hysteresis in cellpotential vs. Li concentration between charge and discharge half-cyclesa very undesirable property for a battery. Again, the origin of thehysteresis is largely unknown. The main advantage of these materials isthat their inherently finely-divided nature augurs well for fastkinetics, an absolute prerequisite if LIB's are to have an impact inhigh current applications (e.g., electric vehicle).

[0232] The anode of the present invention is entirely nano-fabricatedwith molecular precision. It has a large capacity per unit volume tostore lithium at an electrochemical potential near that of lithiummetal, and is protected from the dendrite growth problems and safetyconcerns that plague pure metal anodes. It has extremely fast kineticsfor charging and discharging, but maintains its architectural andchemical integrity in at all states of charge and discharge. Inaddition, there is a means for custom designing the interface betweenthis anode and the electrolyte such that the Li⁰⇄Li⁺¹ redox chemistry ishighly reversible and very low in effective resistance.

[0233] A design for such an anode is one which consists of an array offullerene nanotubes, attached to a metallic support electrode, such asgold-coated copper, and arranged in a hexagonal lattice much like a bedof nails. As shown in FIG. 14, this structure has the virtue that thestorage area for the reduced state of the lithium, Li₀, is down deepchannels either between the nanotubes or down the hollow core of thetubes themselves. Accordingly, the redox chemistry of the lithium isconfined primarily to the exposed ends of the nanotubes, and herederivatization of the nanotube ends provides great opportunities toinsure that this redox chemistry is as reversible as possible.

[0234] 5. Three-Dimensional Self-Assembling SWNT Structures

[0235] The self assembling structures contemplated by this invention arethree-dimensional structures of derivatized SWNT molecules thatspontaneously form when the component molecules are brought together. Inone embodiment the SAM, or two dimensional monolayer, described abovemay be the starting template for preparing a three dimensionalself-assembling structures. Where the end caps of the component SWNTmolecules have mono-functional derivatives the three-dimensionalstructure will tend to assemble in linear head-to-tail fashion. Byemploying multi-functional derivatives or multiple derivatives atseparate locations it is possible to create both symmetrical and nonsymmetrical structures that are truly three-dimensional.

[0236] Carbon nanotubes in material obtained according to the foregoingmethods may be modified by ironically or covalently bondingfunctionally-specific agents (FSAs) to the nanotube. The FSAs may beattached at any point or set of points on the fullerene molecule. TheFSA enables self-assembly of groups of nanotubes into geometricstructures. The groups may contain tubes of differing lengths and usedifferent FSAs. Self-assembly can also occur as a result of van derwaals attractions between derivitized or underivitized or a combinationof derivitized and underivitized fullerene molecules. The bondselectivity of FSAs allow selected nanotubes of a particular size orkind to assemble together and inhibit the assembling of unselectednanotubes that may also be present. Thus, in one embodiment the choiceof FSA may be according to tub length. Further, these FSAs can allow theassembling of two or more carbon nanotubes in a specific orientationwith respect to each other.

[0237] By using FSAs on the carbon nanotube and/or derivitized carbonnanotubes to control the orientation and sizes of nanotubes which areassembled together, a specific three dimensional structure can be builtup from the nanotube units. The control provided by the FSAs over thethree dimensional geometry of the self assembled nanotube structure canallow the synthesis of unique three dimensional nanotube materialshaving useful mechanical, electrical, chemical and optical properties.The properties are selectively determined by the FSA and the interactionof an among FSAs.

[0238] Properties of the self-assembled structure can also be affectedby chemical or physical alteration of the structure after assembly or bymechanical, chemical, electrical, optical, and/or biological treatmentof the self-assembled fullerene structure. For example, other moleculescan be ionically or covalently attached to the fullerene structure ofFSAs could be removed after assembly or the structure could berearranged by for example, biological or optical treatement. Suchalterations and/or modifications could alter or enable electrical,mechanical, electromagnetic or chemical function of the structure, orthe structure's communication or interaction with other devices andstructures.

[0239] Examples of useful electric properties of such a self-assembledgeometric structure include, operation as an electrical circuit, aspecific conductivity tensor, a specific response to electromagneticradiation, a diode junction, a 3-terminal memory device that providescontrollable flow of current, a capacitor forming a memory element, acapacitor, an inductor, a pass element, or a switch.

[0240] The geometric structure may also have electromagnetic propertiesthat include converting electromagnetic energy to electrical current, anantenna, an array of antennae, an array that produces coherentinterference of electomagnetic waves to disperse those of differentwavelength, an array that selectively modifies the propagation ofelectromagnetic waves, or an element that interacts with optical fiber.The electromagnetic property can be selectively determined by the FSAand the interaction of and among FSAs. For example, the lengths,location, and orientation of the molecules can be determined by FSAs sothat an electromagnetic field in the vicinity of the molecules induceselectrical currents with some known phase relationship within two ormore molecules. The spatial, angular and frequency distribution of theelectromagnetic field determines the response of the currents within themolecules. The currents induced within the molecules bear a phaserelationship determined by the geometry of the array. In addition,application of the FSAs could be used to facilitate interaction betweenindividual tubes or groups of tubes and other entities, whichinteraction provides any form of communication of stress, strain,electrical signals, electrical currents or electromagnetic interaction.This interaction provides an “interface” between the self-assemblednanostructure and other known useful devices.

[0241] Choice of FSAs can also enable self-assembly of compositionswhose geometry imparts useful chemical or electrochemical propertiesincluding operation as a catalyst for chemical or electrochemicalreactions, sorption of specific chemicals, or resistance to attack byspecific chemicals, energy storage or resistance to corrosion.

[0242] Examples of biological properties of FSA self-assembled geometriccompositions include operation as a catalyst for biochemical reactions,sorption or reaction site specific biological chemicals agents orstructures; service as a pharmaceutical or therapeutic substance;interaction with living tissue or lack of interaction with livingtissue, or as an agent for enabling any form of growth of biologicalsystems as an agent for interaction with electrical, chemical, physicalor optical functions of an known biological systems.

[0243] FSA assembled geometric structures can also have usefulmechanical properties which include but are not limited to a highelastic to modulus weight ratio or a specific elastic stress tensor.Optical properties of geometric structure an include a specific opticalabsorption spectrums a specific optical transmission spectrum, aspecific optical reflection characteristic, or a capability formodifying he polarization of light.

[0244] Self-assembled structures, or fullerene molecules, alone or incooperation with one another (the collective set of alternatives will bereferred to as “molecule/structure”) can be used to create devices withuseful properties. For example, the molecule/structure can be attachedby physical, chemical, electrostatic, or magnetic means to another toanother structure causing a communication of information by physical,chemical, electrical, optical or biological means between themolecule/structure and other structure to which the molecule/structureis attached or between entities in the vicinity of themolecule/structure. Examples include, but are not limited to physicalcommunication via magnetic interaction, chemical communication viaaction of electrolytes or transmission of chemical agents through asolution, electrical communication via transfer of electronic charge,optical communication via interaction with and passage of any form withbiological agents between the molecule/structure and another entity withwhich those agents interact.

[0245] 6. SWNT Antenna

[0246] Fullerene nanotubes can be used to replace the more traditionalconductive elements of an antenna. For example, an (n,n) tube inconjunction with other materials can be used to form a Schottky barrierwhich would act as a light harvesting antenna. In one embodiment, a(10,10) tube can be connected via sulfur linkages to gold at one end ofthe tube and lithium at the other end of the tube forming a naturalSchottky barrier. Current is generated through photo conductivity. Asthe (10,10) tube acts like an antenna its pumps electrons into oneelectrode, but back flow of electrons is prevented by the intrinsicrectifying diode nature of the nanotube/metal contact.

[0247] In forming an antenna, the length of the nanotube can be variedto achieve any desired resultant electrical length. The length of themolecule is chosen so that the current flowing within the moleculeinteracts with an electromagnetic field within the vicinity of themolecule, transferring energy from that electromagnetic field toelectrical current in the molecule to energy in the electromagneticfield. This electrical length can be chosen to maximize the currentinduced in the antenna circuit for any desired frequency range. Or, theelectrical length of an antenna element can be chosen to maximize thevoltage in the antenna circuit for a desired frequency range.Additionally, a compromise between maximum current and maximum voltagecan be designed.

[0248] A fullerene nanotube antenna can also serve as the load for acircuit. The current to the antenna can be varied to produce desiredelectric and magnetic fields. The length of the nanotube can be variedto provide desired propagation characteristics. Also, the diameter ofthe antenna elements can be varied by combining strands of nanotubes.

[0249] Further, these individual nanotube antenna elements can becombined to form an antenna array. The lengths, location, andorientation of the molecules are chosen so that electrical currentswithin two or more of the molecules act coherently with some known phaserelationship, producing or altering an electromagnetic field in thevicinity of the molecules. This coherent interaction of the currentswithin the molecules acts to define, alter, control, or select thespatial, angular and frequency distributions of the electromagneticfield intensity produced by the action of these currents flowing in themolecules bear a phase relationship determined by the geometry of thearray, and these currents themselves produce a secondary electromagneticfield, which is radiated from the array, having a spatial, angular andfrequency distribution that is determined by the geometry of the arrayand its elements. One method of forming antenna arrays is theself-assembly monolayer techniques discussed above.

[0250] 7. Fullerene Molecular Electronics

[0251] Fullerene molecules can be used to replace traditionalelectrically conducting elements. Thus fullerene molecules orself-assembled fullerene groups can be the basis of electrical circuitsin which the molecule transfers electrical charge between functionalelements of the circuit which alter or control the flow of that chargeor objects in which the flow of electrical current within the objectperforms some useful function such as the redistribution of the electricfield around the object or the electric contact in a switch or aresponse of the object to electromagnetic waves.

[0252] As an example, nanotubes can also be self-assembled to form abridge circuit to provide full wave rectification. This device caninclude four nanotubes, each forming an edge of a square, and fourbuckyballs, one bucky ball would be located at each corner of thesquare. The buckyballs and nanotubes can be derivitized to includefunctionally specific agents. The functionally specific agents formlinkages connecting the buckyballs to the nanotubes and imparting therequired geometry of the bridge.

[0253] A fullerene diode can be constructed through the self-assemblytechniques described above. The diode can be composed of two bucky tubesand a bucky capsule. The bucky capsule can also be derivitized to form azweterrion. For example, the bucky capsule can include two positivegroups such as the triethyl amine cation and two negative groups, suchas CO₂ anion. In one embodiment each end of the bucky capsule isconnected to a (10,10) bucky tube by a disulfide bridge. Thus, sulfurserves as the functionally-specific agent.

[0254] 8. Probes and Manipulators

[0255] The SWNT molecules of the present invention also enable thefabrication of probes and manipulators on a nanoscale. Probe tips forAFM and STM equipment and AFM cantilevers are examples of such devices.Derivatized probes can serve as sensors or sensor arrays that effectselective binding to substrates. Devices such as these can be employedfor rapid molecular-level screening assays for pharmaceuticals and otherbioactive materials. Further, conducting SWNT molecules of the presentinvention may also be employed as an electrochemical probe.

[0256] Similarity probe-like assemblies of SWNT molecules can be usedwith or without derivatives as tools to effect material handling andfabrication of nanoscale devices, e.g., nanoforcepts. In addition, thesemolecular tools can be used to-fabricate MEMS (Micro Electro MechanicalSystems) and also can be employed as connecting elements or circuitelements in NANO-MEMS.

[0257] 9. Composite Materials Containing Carbon Nanotubes

[0258] Composite materials, i.e., materials that are composed of two ormore discrete constituents, are known. Typically, composites include amatrix, which serves to enclose the composite and give it its bulk form,and a structural constituent, which determines the internal structure ofthe component. The matrix deforms and distributes an applied stress tothe structural constituent.

[0259] Although composites are generally extremely strong, theirstrength is generally anisotropic, being much less in the directionperpendicular to the plane of the composite material than any paralleldirection. Because of this characteristic, composites that are formed inlayers or in laminate strips are prone to delamination. Delamination mayoccur when at least one layer of the composite separates from theothers, resulting in a void in the bulk of the composite material. Thisvoid is exceedingly difficult to detect, and with repeated applicationsof stress to the composite element, the composite element will failcatastrophically, without warning.

[0260] Carbon nanotubes may serve as structural constituents incomposite materials. As discussed above, composite materials aregenerally composed of two or more discrete constitutes, usuallyincluding a matrix, which gives the composite its bulk form, and atleast one structural constituent, which determines the internalstructure of the composite. Matrix materials useful in the presentinvention can include any of the known matrix materials presentlyemployed (see e.g. Mel M. Schwartz, Composite Materials Handbook (2d ed.1992)). Among those known matrix materials are resins (polymers), boththermosetting and thermoplastic, metals, ceramics, and cermets.

[0261] Thermosetting resins useful as matrix materials includephthalic/maelic type polyesters, vinyl esters, epoxies, phenolics,cyanates, bismaleimides, and nadic end-capped polyimides (e.g., PMR-15).thermoplastic resins include polysulfones, polyamides, polycarbonates,polyphenylene oxides, polysulfides, polyether ether ketones, polyethersulfones, polyamide-imides, polyetherimides, polyimides, polyarylates,and liquid crystalline polyester. In a preferred embodiment, epoxies-areused as the matrix material.

[0262] Metals useful as matrix materials include alloys of aluminum suchas aluminum 6061, 2024, and 713 aluminum braze. Ceramics useful asmatrix materials include glass ceramics, such as lithiumaluminosilicate, oxides such as alumina and mullite, nitrides such assilicon nitride, and carbides such as silicon carbide. Cermets useful asmatrix materials include carbide-base cermets (tungsten carbide,chromium carbide, and titanium carbide), refractory cements(tungsten-thoria and barium-carbonate-nickel), chromium-alumina,nickel-magnesia iron-zirconium carbide.

[0263] The carbon nanotube structural constituent according to thepresent invention can take any of the forms described herein and knownin the art. Preferably, a fullerene nanotube, i.e., a carbon nanotubewith molecular perfection, is used. Fullerene nanotubes are made of asingle continuous sheet of hexagonal graphene joined perfectly to form atube with a hemifullerene cap at either end. It may be either a truesingle-walled fullerene tube itself with hemispherical caps attached, orit may refer to one derived from such a closed tube by cutting, etchingoff the ends, etc. Alternatively, it is a multi-walled fullerenenanotube constructed of some number of single-walled fullerene nanotubesarranged one inside another. Arc-grown multi-walled nanotubes (MWNT),though approaching the fullerene ideal, are still not perfect. They havesignificant structural defects of lesions at least every 100 nm or so ormore in their multiple walls. The single-walled carbon nanotubes made bythe laser/oven method, however, appear to be molecularly perfect. Theyare fullerene nanotubes, and fibers made from them are true fullerenefibers.

[0264] The single-wall fullerene nanotubes may be metallic (formed inthe armchair or (n,n) configuration) or any other helicityconfiguration. The nanotubes may be used in the form of short individualtubular molecules cut to any appropriate length. Cut nanotubes have theheretofore unachievable advantage of providing strengthening andreinforcement on a molecular scale. As they approach the micron scale inlength, however, they become very flexible while still retaining therigid tubular properties on a molecular scale.

[0265] Aggregates of individual tubes referred to herein as ropes havingup to about 10³ carbon nanotubes may also be employed. Ropes of carbonnanotubes produced as described above have the advantage of anentangled, loopy physical configuration on a micron scale that resultsin a Velcro-like interaction with each other and matrix material whilestill retaining the rigid tubular bundle structure on a molecular level.

[0266] Macroscopic carbon nanotube fibers (having at least 10⁶individual tubes), in either the continuous or random fiber formsdescribed above, can also be employed to form the composite of thepresent invention. Ropes and fibers may be cut into desired lengths asdescribed herein or used as tangled, loopy felts or the like.

[0267] The present invention also contemplates composites in whichcarbon nanotubes are present in two or more of the foregoing forms,e.g., mixed in the same matrix area or having different nanotube formsin different areas of the matrix. Selection of the carbon nanotube formwill depend on the nature of the composite and its desired finalproperties. The carbon nanotubes are preferably cleaned and purified asdescribed herein before use.

[0268] The nanotubes, ropes, or fibers used in the composites may alsobe derivatized as described above. End cap derivatization of carbonnanotubes can facilitate the bonding of the carbon nanotubes to eachother or to the matrix material. While pure carbon nanotubes generallycontain side walls that are entirely uniform (consisting of an array ofthe hexagonal carbon lattice similar to that of graphite), it ispossible to introduce defects or create bonding sites in the sidewallsto facilitate bonding adhesion to the matrix material. One example wouldbe to incorporate an impurity such as Boron atoms in the side wall. Thewall defect or bonding site thus created may facilitate interaction ofthe nanotube with the matrix material through physical or chemicalforces. It is additionally possible that such defect or bonding site mayfacilitate chemical reactions between the tube itself and the matrixmaterial in a way that affects the properties of the composite materialformed. As described above, the carbon nanotube material may also have apart of its lattice replaced with boron nitride.

[0269] Other fibrous structural constituents, both organic andinorganic, may also be used in conjunction with the carbon nanotubematerials of this invention. Examples of organic constituents that maybe used include cellulose Examples of inorganic constituents includecarbon, glass (D,E, and S-type), graphite, silicon oxide, carbon steel,aluminum oxide, beryllium, beryllium oxide, boron, boron carbide, boronnitride, chromium, copper, iron, nickel, silicon carbide, siliconnitride, FP alumina yarn manufactured by DuPont, Nextelalumina-boriasilica and zirconia-silica manufactured by 3M, Saffil HTzircona and alumina manufacture by ICI, quartz, molybdenum, Rene 41,stainless steel, titanium boride, tungsten, and zirconium oxide.

[0270] Fabrication of the composite of the present invention can employany of the well-known techniques for combining the matrix material withthe structural constituent. Carbon nanotubes, as individual tubularmolecules or as ropes, can be dispersed in a liquid carrier, e.g. wateror organic solvents, to facilitate incorporation into a matrix material.Macroscopic carbon nanotube fibers can be handled in the conventionalmanner employed in the current processes using carbon or graphitefibers.

[0271] The carbon nanotube structural constituent may be uniformly mixedwith a matrix material precursor (polymer solution, pre-fired ceramicparticles or the like) and the converted to a composite by conventionaltechniques. Structural layers or components (e.g., felts or bucky paper)can also be preformed from the carbon nanotube materials and impregnatedwith a prepolymer solution to form the composite.

[0272] The carbon nanotube structural constituents may also be used toimprove the properties of conventional composite materials. One suchexample involves composites built-up of fibrous laminates impregnatedand bonded with a polymer matrix material. Graphite fiber fabric layersbonded with an epoxy system is a well-known example of such a composite.By using carbon nanotube ropes or fibers that exhibit a 3-D loopystructure added only at the epoxy/graphite interfaces resistance todelamination of the resulting laminar composite can be substantiallyincreased. The carbon nanotube material can be dispersed in the epoxysystem before impregnation (or premixed into one of the reactivecomponents thereof). The carbon nanotube material can also be dispersedin a liquid carrier and sprayed or otherwise applied to the laminate aseach graphite fabric layer is added.

[0273] A single-walled fullerene nanotube such as the (10,10) tube isunique as a component in a composite. From one perspective, it is simplya new molecular polymer, like polypropylene, Nylon, Kevlar, or DNA. Itis about the diameter of the DNA double-helix, but vastly stiffer inbending and stronger in tension. Long chain polymers are characterizedby their persistence length (the distance one has to travel along thelength before there is a substantial change in the chain direction underconditions of normal Brownian motion). For polypropylene, this distanceis only about 1 nm, and for the DNA double-helix it is about 50 nm. Butfor a single (10,10) fullerene nanotube, it is greater than 1000 nm. Soon the persistence length scale of normal polymer molecules such asthose that would constitute the continuous phase of a composite materialfullerene nanotubes are effectively rigid pipes.

[0274] Yet on the length scale of a micron or so, a single (10,10)fullerene nanotube is a highly flexible tube, easily becoming involvedwith other nanotubes in tangles with many loops. These tangles and loopsprovide two new opportunities in the internal mechanics of composites:(1) the continuous phase can interpenetrate through these loops,resulting in the nanotubes being intimately “tied” to this phase on asub-micron length scale, and (2) with processing by flow and shear ofthe composite mixture before it sets up, the loops can become entangledin one another and pulled taught. As a result, composites made offullerene tangles have extra toughness, strength, and resistance todelamination failure.

[0275] Fullerenes like C₆₀ or C₇₀ are known to be effectively spongesfor free radicals. Similarly fullerene nanotubes such as the (10,10)tube will chemisorb free radicals like methyl, phenyl, methoxy, phenoxy,hydroxy, etc., to their sides As with the smaller fullerenes, thesechemisorbed species do not substantially weaken the cage network(dissociation at high temperatures simply desorbes the surface species,maintaining the fullerene structure intact). Accordingly, in a compositecontaining fullerene nanotubes, one can achieve a covalent coupling tothe continuous polymer phase simply by attaching pendant groups on thepolymer which produces a free radical upon heating or photolysis withultraviolet light. The azo-linkage as found in azo-bis-isobutylnitrile,for example, is quite effective as a photo activated free radicalsource.

[0276] The unique properties of the carbon fiber produced by the presentinvention also permit new types of composite reinforcement. It ispossible, for example, to produce a composite fiber/polymer withanisotropic properties. This can, for example, be accomplished bydispersing a number of metallic carbon nanotube fiber (e.g., from (n,n)SWNTs) in a prepolymer solution (E.g., a poly methymethacrylate) andusing an external electric field to align the fibers, followed bypolymerization. electrically conductive components can also be formedusing the metallic forms of carbon nanotubes.

[0277] Applications of these carbon nanotubes containing compositesinclude, but are not limited to all those currently available forgraphite fibers and high strength fibers such as Kevlar, includingstructural support and body panels and for vechicles, includingautomobiles, trucks, and trains, tires, aircraft components, includingairframes stabilizers, wing skins, rudders, flaps, helicopter rotorblades, rudders, elevators ailerons, spoilers, access doors, enginepods, and fuselage sections, spacecraft, including rockets, space ships,and satellites, rocket nozzles, marine applications, including hullstructures for boats, hover crafts, hydrofoils, sonar domes, antennas,floats, buoys, masts, spars, deckhouses, fairings, and tanks, sportinggoods, including golf carts, golf club shafts, surf boards, hang-gliderframes, javelins, hockey sticks, sailplanes, sailboards, ski poles,playground equipment, fishing rods, snow and water skis, bows, arrows,racquets, pole-vaulting poles, skateboards, bats, helmets, bicycleframes canoes, catamarans, oars, paddles, and other items, mass producedmodular homes, mobile homes, windmills, audio speakers, furnitureincluding chairs, lamps, tables, and other modern furniture designs,soundboards for string instruments, lightweight armored products forpersonnel, vehicle, and equipment protection, appliances, includingrefrigerators, vacuum cleaners, and air conditioners, tools, includinghammer handles, ladders, and the like, biocompatible implants,artificial bones, prostheses, electrical circuit boards, and pipes ofall kinds.

EXAMPLES

[0278] In order to facilitate a more complete understanding of theinvention, a number of Examples are provided below. However the scope ofthe invention is not limited to specific embodiments disclosed in theseExamples, which are for purposes of illustration only.

Example 1 Oven Laser vaporization

[0279] The oven laser vaporization apparatus described in FIG. 1 andalso described by Haufler et al., “Carbon Arc Generation of C₆₀,” Mat.Res. Soc. symp. Proc., Vol 206, p. 627 (1991) and by U.S. Pat. No.5,300,203 was utilized. An Nd:YAG laser was used to produce a scanninglaser beam controlled by a motor-driven total reflector that was focusedto a 6 to 7 mm diameter spot onto a metal-graphite composite targetmounted in a quartz tube. The laser beam scans across the target'ssurface under computer control to maintain a smooth, uniform face on thetarget. The laser was set to deliver a 0.532 micron wavelength pulsedbeam at 300 milliJoules per pulse. The pulse rate was 10 hertz and thepulse duration was 10 nanoseconds (ns).

[0280] The target was supported by graphite poles in a 1-inch quartztube initially evacuated to 10 m Torr. and then filled with 500 Torr.argon flowing at 50 standard cubic centimeters per second (sccm). Giventhe diameter of the quartz tube, this volumetric flow results in alinear flow velocity through the quartz tube in the range of 0.5 to 10cm/sec. The quartz tube was mounted in a high-temperature furnace with amaximum temperature setting of 1200° C. The high-temperature furnaceused was a Lindberg furnace 12 inches long and was maintained atapproximately 1000° to 1200° C. for the several experiments inExample 1. The laser vaporized material from the target and thatvaporized material was swept by the flowing argon gas from the area ofthe target where it was vaporized and subsequently deposited onto awater-cooled collector, made from copper, that was positioned downstreamjust outside the furnace.

[0281] Targets were uniformly mixed composite rods made by the followingthree-step procedure: (i) the paste produced from mixing high-puritymetals or metal oxides at the ratios given below with graphite powdersupplied by Carbone of America and carbon cement supplied by Dylon atroom temperature was placed in a 0.5 inch diameter cylindrical mold (ii)the mold containing the paste was placed in a hydraulic press equippedwith heating plates, supplied by Carvey, and baked at 130° C. for 4 to 5hours under constant pressure, and (iii) the baked rod (formed from thecylindrical mold) was then cured at 810° C. for 8 hours under anatmosphere of flowing argon. For each test, fresh targets were heated at1200° C. under flowing argon for lengths of time, typically 12 hours,and subsequent runs with the same targets proceeded after 2 additionalhours heating at 1200° C.

[0282] The following metal con ions were used in this example cobalt(1.0 atom per cent), copper (0.6 atom per cent), niobium (0.6 atom percent), nickel (0.6 atom per cent), platinum (0.2 atom per cent), amixture of cobalt and nickel (0.6 atom per cent/0.6 atom per centrespectively ), a mixture of cobalt and platinum (0.6 atom per cent/0.2atom per cent respectively), a mixture of cobalt and copper (0.6 atomper cent/0.5 atom per cent respectively), and a mixture of nickel andplatinum (0.6 atom per cent/0.2 atom per cent respectively). Theremainder of the mixture was primarily graphite along with small amountsof carbon cement. Each target was vaporized with a laser beam and thesoots collected from the water cooled collector were then collectedseparately and processed by sonicating the soot for 1 hour in a solutionof mechanol at room temperature and pressure (other useful solventsinclude acetone, 1,2-dichloroethane. 1-bromo, 1,2-dichloroethane, andN,N-dimethylformamide). With one exception, the products collectedproduced a homogeneous suspension after 30 to 60 minutes of sonicationin methanol. One sample vaporized from a mixture of cobalt nickel andgraphite was a rubbery deposit having a small portion that did not fullydisperse even after 2 hours of sonication in methanol. The soots werethen examined using a transmission electron microscope with a beamenergy of 100 keV (Model JEOL 2010).

[0283] Rods (0.5 ih diameter having the Group VIII transition metal ormixture of two VII transition metals described above were evaluated inthe experimental apparatus to determine the yield and quality ofsingle-wall carbon nanotubes produced. No multi-wall carbon nanotubeswere observed in the reaction products. Yields always increased withincreasing oven temperature up to the limit of the oven used (1200° C.).At 1200° C. oven temperature, of the single metals utilized in theexample, nickel produced the greatest yield of single-wall carbonnanotubes followed by cobalt. Platinum yielded a small number ofsingle-wall carbon nanotubes and no single-wall carbon nanotubes wereobserved when carbon was combined only with copper or only with niobium.With respect to the mixtures of two Group VIII transition metalcatalystswith graphite, the cobalt/nickel mixture and the cobalt/platinummixtures were both approximately equivalent and both were the bestoverall catalyst in terms of producing yields of single-wall carbonnanotubes. The yield of single-wall carbon nanotubes for both of thesetwo metal mixtures were 10 to 100 times the yield observed when only oneGroup VIII transition metal was used. The mixture of nickel and platinumwith graphite also had a high yield of single-wall carbon nanotubes thana single metal alone. The cobalt/copper wit graphite priced a smallquantity of single-wall carbon nanotubes.

[0284] The cobalt/nickel mixture with graphite and the cobalt/platinummixture with graphite both produced deposits on the water cooledcollector that resembled a sheet of rubbery material. The deposits wereremoved intact. The cobalt/platinum mixture produced single-wall carbonnanotubes in a yield estimated at 15 weight per cent of all of thecarbon vaporized from the target. The cobalt/nickel mixture producedsingle-wall carbon nanotubes at yields of over 50 wt% of the amount ofcarbon vaporized.

[0285] The images shown in FIGS. 15A through 15E are transmissionelectron micrographs of single-wall carbon nanotubes produced byvaporizing a target comprising graphite and a mixture of cobalt andnickel (0.6 atom per cent/0.6 atom per cent respectively) at an oventemperature of 1200° C. FIG. 15A shows a medium-magnification view(where the scale bar represents 100 mm) showing that almost everywhere,bundles of single-wall carbon nanotubes are tangled together with othersingle-wall carbon nanotube FIG. 15B is a high-magnification image ofone bundle of multiple single-wall carbon nanotubes that are all roughlyparallel to each other. The single-wall carbon nanotubes all have adiameter of about 1 nm, with similar spacing between adjacentsingle-wall carbon nanotubes. The single-wall carbon nanotubes adhere toone another by van der Waals forces.

[0286]FIG. 15C shows several overlapping bundles of singe-wall carbonnanotubes, again showing the generally parallel nature of eachsingle-wall nanotube with other single-wall carbon nanotubes in the samebundle, and showing the overlapping and bending nature of the variousbundles of single-wall carbon nanotubes. FIG. 15D shows severaldifferent bundles of single-wall carbon nanotubes, all of which are bentat various angles or arcs. One of the bends in the bundles is relativelysharp, illustrating the strength and flexibility of the bundle ofsingle-wall carbon nanotubes. FIG. 15E shows a crowsectional view of abundle of 7 single-wall carbon nanotubes, each running roughly parallelto the others. All of the transmission electron micrographs in FIGS. 15Athrough 10E clearly illustrate the lack of amorphous carbon overcoatingthat is typically seen in carbon nanotubes and single-wall carbonnanotubes grown in arc-discharge methods. The images in FIG. 15A through15E also reveal that the vast majority of the deposit comprisessingle-wall carbon nanotubes. The yield of single-wall carbon nanotubesis estimated to be about 50% of the carbon vaporized. The remaining 50%consists primarily of fullerenes, multi-layer fullerenes (fullereneonions) and/or amorphous carbon.

[0287]FIGS. 15A through 15E show transmission electron microscope imagesof the products of the cobalt/nickel catalyzed carbon nanotube materialthat was deposited on the water cooled collector in the laservaporization apparatus depicted in FIG. 1 Single-wall carbon nanotubeswere typically found grouped in bundles in which many tubes ran togetherroughly parallel in van der Waals contact over most of or their length.The grouping resembled an “highway” structure in which the bundles ofsingle-wall carbon nanotubes randomly crises-crossed each other. Theimages shown in FIGS. 15A through 15E make it likely that a very highdensity of single-wall nanotubes existed iii the gas phase in order toproduce so many tubes aligned as shown when landing on the cold watercooled collector. There also appeared to be very little other carbonavailable to coat the single-wall carbon nanotubes prior to theirlanding on the water cooled collector in the alignment shown. Evidencethat single-wall carbon nanotubes grow in the gas phase, as opposed tofor example on the walls of the quartz tube, was provided in earlierwork on multi-walled carbon nanotubes using the same method. See Guo etal., “Self-Assembly of Tubular Fullerenes,” J. Phys. Chem., Vol, 99, p.10694 (1995) and Saito et al., “Extrusion of Single-Wall CarbonNanotubes via Formation of Small Particles Condensed Near An EvaporationSource,” Chem. Phys. Lett., Vol. 236, p. 419 (1995). The high yield ofsingle-wall carbon nanotubes in these experiments is easily remarkablebecause the soluble fullerene yield was found to be about 10 weight percent, and much of the remaining carbon in the soot product consisted ofgiant fullerenes and multi layer fullerenes.

Example 2. Laser-vaporization to produce longer single-wall carbonnanotubes.

[0288] In this example, a laser vaporization apparatus similar to thatdescribed by FIG. 1 was used to produce longer single-wall carbonnanotubes. The laser vaporization apparatus was modified to include atungsten wire strung across the diameter of a quartz tube mounted in anoven. The tungsten wire was placed downstream of the target so that thewire was 1 to 3 cm downstream from the downstream side of the target (13to 15 cm downstream from the surface of the target being vaporized).Argon at 500 Torr, was passed through the quartz tube at a flow rateequivalent to a linear velocity in the quartz tube of about 1 cm/sec.The oven was maintained at 1200° C. and Group VIII transition-metalswere combined at 1 to 3 atom% with carbon to make the target.

[0289] The pulsed laser was operated as in Example 1, for 10 to 20minutes. Eventually, a tear drop shaped deposit formed on the tungstenwire, with portions growing to lengths of 3 to 5 nm. The depositresembled eyelashes growing on the tungsten wire. Examination of thedeposit revealed bundles of millions of single-wall carbon nanotubes.

Example 3 Two Laser Vaporization

[0290] Graphite rods were prepared, as described in Example 1 usinggraphite, graphite cement and 1.2 atom % of a mixture of 50 atom %cobalt powder and 50 atom % nickel powder. The graphite rods werepressed into shape and then formed into targets as described inExample 1. The graphite rods were then installed as Nets in an apparatusas diagramed in FIG. 2, except tungsten wire 32 was not used. A quartztube holding the graphite rod targets was placed in an oven heated to1200° C. Argon gas which had been catalytically purified to remove watervapor and oxygen was passed through the quartz tube at a pressure ofabout 500 Torr and a flow rate of about 50 sccm although flow rates inthe range of about 1 to 500 scan (standard cubic centimeters perminute), preferably 10 to 100 sccm are also useful for a 1 inch diameterflow tube. The first laser was set to deliver a 0.532 micron wavelengthpulsed beam at 250 mJ per pulse. The pulse rate was 10 Hz and the pulseduration was 5 to 10 ns. A second laser pulse struck the target 50 nsafter the end of the first pulse. The second laser was set to deliver a1.064 micron wavelength pulsed beam at 300 ml per pulse. The pulse ratewas 10 Hz and the pulse duration was 5 to 10 ns. The first laser wasfocused to a 5 mm diameter spot on the target and the second laser wasfocused to a 7 mm diameter gaussian spot having the same center point onthe target as the spot from the first laser., About 1/10 th of a secondafter the second laser hit the target, the first and second lasers firedagain and this process was repeated until the vaporization step wasstopped

[0291] About 30 mg/hr of the raw product from the laser vaporization ofthe target surface was collected downstream. The raw product comprised amat of randomly oriented single-wall carbon nanotubes. The raw productmat is made up almost entirely of carbon fibers 10-20 nm in diameter and10 to 1000 microns long.

[0292] About 2 mg of the raw product mat was sonicated in 5 ml methanolfor about 0.5 our at room temperature. Transmission Electron Microscope(TEM) analysis of the sonicated product proved that the product wascomprised mostly of ropes of single-wall carbon nanotubes, bundles of 10to 1000 single-wall carbon nanotubes aligned with each other (except foroccasional branching) having a reasonably constant rope diameter overthe entire length of the rope. The ropes were more than 100 microns longand consisting of uniform diameter single-wall carbon nanotubes. About70to90wt% of the product is in the form of ropes. The individualsingle-wall carbon nanotubes in the ropes all terminate within 100 nm ofeach other at the end of the rope. More than 99% of the single-wallcarbon nanotubes appear to be continuous and free from carbon latticedefects over all of the length of each rope.

Example 4 Procedure for Purifying Single-Wall Nanotube Material to >99%

[0293] Material formed by the laser production method described in U.S.Ser. No. 081687,665 was purified as follows to obtain a preparationenriched in nanotubes. 200 mg of the raw laser-produced single-wallnanotube material (estimated yield of 70%) was refluxed in 2.6 M aqueousnitric acid solution for 24 hours. At 1 atm pressure the refluxtemperature was about 1200° C. The solution was then filtered through a5 micron pore size TEFLON filter (Millipore Type LS), and the recoveredsingle-wall nanotubes were refluxed for a second 24 hr period in freshnitric acid solution (2.6 M). The solution was filtered again to recoverthe single-wall nanotube material, and the material recovered from thefiltration step was sonicated in saturated NaOH in ethanol at roomtemperature for 12 hours. The ethanolic solution was filtered to recoverthe single-wall nanotube material, and the material recovered wasneutralized by refluxing in 6M aqueous HCI for 12 hours. The nanotubematerial was recovered from the aqueous acid by filtration, and baked at850° C. in 1 atm H₂ gas (flowing at 1-10 sccm through a 1″ quartz tube)for 2 hours. The yield was 70 mg of recovered purified material.Detailed TEM, SEM and Raman spectral examination showed it to be >99%,pure, with the dominant impurity being a few carbon-encapsulated Ni/Coparticles.

Example 5 Procedure for Cutting SWNT into Tubular Carbon Molecules

[0294] Bucky paper (˜100 nicrons thick) obtained by the filtration andbaking of purified SWNT material as described in Example 1 was exposedto a 2 GEV beam of Au^(+×)ions in the Texas A&M SuperconductingCyclotron Facility for 100 minutes. The irradiated paper had 10-100 nmbullet holes on average every 100 nm along the nanotube lengths. Theirradiated paper was refluxed in 2.6 M nitric acid for 24 hours to etchaway the amorphous carbon produced by the fast ion irradiation,filtered, sonicated in ethanol/potassium hydroxide for 12 hours,refiltered, and then baked in vacuum at 1100° C. to seal off the ends ofthe cut nanotubes.

[0295] The material was then dispersed in toluene while sonicating. Theresulting tubular molecules which averaged about 50-60 mn in length wereexamined via SEM and TEM.

Example 6 Assembly of a SWNT Array

[0296] About 10⁶ (10,10) nanotube molecules with lengths 50-60 nm areprepared as described above, are derivatized to have an ˜SH group at oneend and allowed to form a SAM molecular array of SWNT molecules on asubstrate coated with gold in which the tubular molecules are alignedwith their long axis parallel and the ends of the tubes forming a planeperpendicular to the aligned axes.

Example 7 Growth of a Continuous Macroscopic Carbon Fiber

[0297] The array according to Example 6 can be used to grow a continuousmacroscopic carbon fiber in the apparatus shown in FIGS. 6 and 7. Theends of the nanotubes (which form the plane perpendicular to the axes ofthe tubes) of the array are first opened. For the 2D assembly ofnanotubes on the gold covered surface, the assembly can be made to bethe positive electrode for electrolytic etching in 0.1 M KOH solution,which will open the tips of the nanotubes.

[0298] Ni/Co metal clusters are then vacuum deposited onto the open endsof the assembled nanotubes in the SAM. Preferably, metal clusters 1 nmin diameter are arranged so that one such Ni/Co catalyst nanoparticlesits on the top opening of every nanotube in the nanotube array.

[0299] The Ni/Co capped nanotubes in the am are heated in a vacuum up to600° C., pyrolyzing off all but the carbon nanotubes and the Ni/Coparticles. Once the pyrolysis is complete, a flow of ethylene gas isstarted, and the tubes elongate in the direction of the aligned axes toform a carbon fiber of macroscopic diameter. If a significant portion ofthe Ni/Co particles deactivate, it may be necessary to electrochemicallyetch the tips open and clean the assembly again, and repeat steps ofapplying the Ni/Co catalyst particles and reinitiating growth of thearray. A continuous fiber of about 1 micro in diameter is continuouslyrecovered at room temperature on the take-up roll.

Example 8 Production of Fullerene Pipes and Capsules

[0300] Single-walled fullerene nanotubes were prepared by an apparatuscomprising a 2.5 cm by 5 cm cylindrical carbon target (with a 2 atom %of a 1:1 mixture of cobalt and nickel) that was rotated about itsprinciple axis in flowing argon (500 torr, 2 cm sec⁻¹) in a 10 cmdiameter fused silica tube heated to 1100° C. Two pulsed laser beams(ND:YAG 1064 nm, l J pulse⁻¹, 30 pulse s⁻¹, 40 ns delay) were focused toa 7 mm diameter spot on the side of the rotating target drum and scannedunder computer control along the length of the drum, alternating fromthe left to the right side of the drum so as to change the angle ofincidence on the target surface to avoid deep pitting. This method hasthe advantage of producing 20 grams of material in two days ofcontinuous operation.

[0301] The raw material fined by the apparatus was purified by refluxingin nitric acid followed by filtration and washing pH=10 water withTriton X-100 surfactant. The net yield of purified fullerene fibers fromthis method depends on the initial quality of the raw material, which istypically in the range of I10-20/% by weight. The molecular perfectionof the side walls, a characteristic of fullerene fibers, allows thesefibers to survive the refluxing.

[0302] The fullerene ropes were highly tangled with one other. Thefullerene ropes frequently occurred in fullerene toroids (“cropcircles”), which suggests that the rope are endless. This is due to vander Walls adherence between the “live” ends of the ropes and the sidesof other ropes during the high-yield growth process in the argonatmosphere of the laser/oven method. The growing rope ends wereeliminated in collisions with another live rope end that was growingalong the same guiding rope from the opposite direction. In onedimension, collisions are unavoidable.

[0303] Ends were created from the tangled, nearly endless ropes by manytechniques, ranging from cutting the ropes with a pair of scissors tobombarding the ropes with relativistic gold ions. Here, the ropes werecut by sonicating them in the presence of an oxidizing acid, such asH₂SO₄/HNO₃. The cavitation produced local damage to the tubes on thesurface of the ropes, which activated them for chemical attack by theoxidizing acid. As the acid attacked the tube, the tube was completelycut open and the tube slowly etched back, with its open end unable tore-close at the moderate temperature. Nanotubes underlying the now-cutsurface tube on the rope were exposed, and subsequent cavitation-induceddamage resulted in the cutting of the entire rope. The cut nanotubeswere subjected to further oxidizing acid treatment in order to ensurethat they are molecularly perfect and chemically clean.

[0304] The length distribution of the open-ended tubes is shortenedsystematically with exposure time to the acid. In 3/1 concentratedsulfuric acid/nitric acid, at 70° C., the average cut nanotube wasshortened at a rate of 130 nm hr⁻¹. In a 4/1 sulfuric acid/30% aqueoushydrogen peroxide (“piranha”) mixture at 70° C. the shortening rate wasapproximately 200 nm hr⁻¹. This etching rate is sensitive to the chiralindex of the nanotubes (n,m), with all “arm chair” tubes (n=m) having adistinct chemistry from the “zig-zag” tubes (m=0), and to a lesserextent with-tubes of intermediate helical angle (n=m).

[0305] The cut fullerene tubes material formed stable colloidalsuspensions in water with the assistance of surfactants such as sodiumdodecyl sulfate or a non-ionic surfactant such as Triton X-100. Thesuspensions were separated as a function of nanotube length.

[0306] AFM imaging of the cut nanotube pieces on graphite revealed thatmany nanotubes are individuals, but that a majority of the nanotubeswere in van der Walls contact with each other The nanotubes with lengthsof greater than 100 nm may be closed by true hemifullerene end caps,which form sealed fullerene capsules when annealed in a vacuum at1000-1200° C.

Example 9 Production and Purification of Fullerene Pipes and Capsules

[0307] Referring to FIGS. 16A-C, a SEM image of raw SWNT felt materialis shown n FIG. 16A, while the same material after purification is shownin FIGS. 16B-C. The abnormally low quality initial starting materialemphasizes the effectiveness of the following purification process. Theraw sample (8.5 gm) was refluxed in 1.21 of 2.6 M nitric acid for 45hours. Upon cooling, the solution was transferred to PTFE centrifugetubes and spun at 2400 g for 2 hours. The supernatant acid was decantedoff, replaced by de-ionized water, vigorously shaken to re-suspend thesolids, followed by a second centrifuge/decant cycle. The solids tore-suspend in 1.8 l water with 20 ml Triton X-100 surfactant andadjusted to a pH of 10 with sodium hydroxide. The suspension was thentransferred to the reservoir of a tangential flow filtration system(MiniKros Lab System, Spectrum, Laguna Hills, Calif.). The filtercartridge used (M22M 600 0.1 N, Spectrum) had mixed cellulose esterhollow fibers of 0.6 mm diameter, 200 nm pores and a total surface areaof 5600 cm². The buffer solution consisted of 44 1 of 0.2 vol % TritonX-100 in water of which the first 34 1 were made basic (pH 10) withsodium hydroxide, and the final 101 at pH 7. The cartridge inletpressure was maintained at 6 psi. A control valve was added to the exitso that the outflow rate was restricted to 70 ml min⁻¹. The result was astable suspension of purified SWNT for which the SEM image in FIG. 16Bis typical Filtration of this suspension produces a paper of tangledSWNT which resembles carbon paper in appearance and feel. As is evidentin the SEM image of FIG. 16C. the torn edge of this “bucky paper” showsthat the tearing process produces a substantial alignment of SWNT ropefibers. The overall yield of purified SWNT from this abnormally poorstarting material was 9% by weight.

[0308]FIG. 17 shows a taping mode AFM image of cut fullerene nanotubes(pipes) electrodeposited m a stable colloidal suspension onto highlyoriented pyrolytic graphite (HOPG). The tubes had a tendency to align120° C. to one another. They are in registry with the g graphite latticeAFM measurements of the heights of these cut tubes revealed that roughlyhalf were single tubes 1-2 nm in diameter whereas the rest are ofaggregates of several tubes in van der Waals contact. These cut tubeswere prepared in a two step process t and polishing. In a typicalexample, 10 mg of the purified SWNT “bucky paper” (shown in FIG. 16B)was suspended in 40 ml of a 3: l mixture of concentrated H₂SO₄/HNO₃ in a100 ml test tube and sonicated in a water bath (Cole Palmer model B3-R,55 kHz) for 24 hours at 35-40 ° C. The resultant suspension was thendiluted with 200 ml water and the larger cut SWNT tubes were caught on a100 nm pore size filter membrane (type YCTP, Millipore corp., Bedford,Mass.), and washed with 10 mM NaOH solution. These cut tubes were thenfarther polished (chemically cleaned) by suspension in a 4:1 mixture ofconcentrated H₂SO₄ 30% aqueous H₂O₂ and stirring at 70° C. for 30minutes. After filtering and washing again on a 100 nm filter, the cutnanotubes were suspended at a density of 0.1 mg/ml in water with the aidof 0.5 wt % Triton X-100 suit. The electrodeposition was performed byplacing 20 μl of the nanotube suspension on the ice of a freshly cleavedHOPG substrate (Advanced Ceramics, Cleveland, Ohio), confining thedroplet within a Vitron O-ring (4 mm o.d., 1.7 mm thick), capping thetrapped suspension with a stainless steel electrode on top of theO-ring, and applying a steady voltage of 1.1 V for 6 minutes. Whensuspended in water, the nanotubes are negatively charged and aretherefore driven by the electric field onto the HOPG surface. Afterdeposition the HOPG/nanotube surface was washed with methanol on aspin-coater in order to remove the water and the Triton X-100surfactant.

[0309]FIG. 18 shows the Field Flow Fractionation (FFF) of cut fullerenenanotube “pipes” in aqueous suspension. A 20 μl sample of 0.07 mg/mg cutnanotube suspension in 0.5% aqueous Triton X-100 was injected into across-flow FFF instrument (Model F-1000-FO, FFFractionation, LLC, SaltLake City, Utah) operating with 0.007% Triton X-100 in water mobilephase at 2 ml min⁻¹, and a cross-flow rat of 0.5 ml min⁻¹. The solidcurve (left vertical axis) of FIG. 18A shows the light scatteringturbidity (at 632.8 m, wavelength) of the eluting nanotubes as afunction of total eluent volume since ejection. The open circles (rightaxis) plot the estimate radius of gyration of the nanotubes as measuredby a 16 angle light scattering instrument (SAW DSP, Wyatt Technology,Santa Barbara, Calif.). FIGS. 18B, 18C, and 18D show nanotube lengthdistributions from FFF eluent fractions 1, 3, and 5, respectively, asmeasured from AFM images of the suspended fullerene nanotubeselectrodeposited on HOPG as in FIG. 17.

[0310]FIG. 19 shows-an AFM image of a fullerene nanotube “pipe” tetheredto two 10 nm gold spheres, one at either end. The tube waselectrodeposited onto HOPG graphite from a suspension of a mixture ofsuch tubes with colloidal gold particles (sigma Chemical Co.) in water.The irregularly shaped features in the image are due to residualdeposits of the Triton X-100 surfactant used to stabilize thesuspension. The nanotube-to-gold tethers were constructed of alkyl thiolchains covalently attached to the open ends of the tubes. Presumingthese open ends were terminated with many carboxylic acid groups as aresult of the acid etching in previous processing, they were convertedto the corresponding acid chloride by reacting them with SOCl₂. Thederivitized tubes were then exposed to NH_(2—)(CH₂)_(16 —)SH in tolueneto form the desired tethers, with the thiol group providing a strongcovalent bonding side for a gold particle. Most tubes derivitized thisway have a single gold particle bound to at least one of their ends, asrevealed by extensive AFM imaging.

Example 10 Composite Material Containing Carbon Nanotubes

[0311] One gram of purified single walled fullerene nanotubes isdispersed in 1 liter of dichloro-ethane, together with 10 grams of Eponepoxy. The hardener is added to the solvent removed by vacuum rotaryevaporation. The resultant fullerene nanotube epoxy composite is thencured at 100° C. for 24 hours.

[0312] Alternatively, a carbon fiber, fullerene nanotube composite canbe prepared by drawing one or more continuous carbon fibers or wovencarbon fiber tapes through a vat containing the above dichloroethaneepoxy nanotube suspension, and then winding this impregnated tape arounda desired form. After curing in an autoclave in a fashion known in thecarbon fiber-epoxy composite industry (see, e.g., D.L. Chung, CarbonFiber Composites (1994)), a composite of superior delaminationresistance is produced. The fullerene nanotubes within the compositestrengthen the epoxy between the carbon fiber layers. A superiorcomposite is produced if one uses fullerene fibers for both the woventape layers and the tangled nanotube strengtheners within the epoxyphase.

[0313] Modification and variations of the methods, apparatus,compositions and articles of manufacture described herein will beobvious to those skilled in the art from the foregoing detaileddescription. Such modifications and variations are intended to come withthe scope of the appended claims.

We claim:
 1. A method for purifying a mixture comprising single-wallcarbon nanotubes and amorphous carbon contaminate, said methodcomprising the steps of: (a) heating said are under oxidizing conditionssufficient to remove the said amorphous carbon and (b) recovering aproduct comprising at least about 80% by weight of single-wall carbonnanotubes.
 2. method of claim 1 wherein said oxidizing conditionscomprise an aqueous solution of an inorganic oxidant.
 3. The method ofclaim 2 wherein said inorganic oxidant is selected from the groupconsisting of nitric acid, a mixture of sulfuric acid and hydrogenperoxide, potassium permanganate and mires thereof.
 4. The method ofclaim 2 wherein said aqueous solution is heated to reflux.
 5. The methodof claim 2 additionally comprising the step of subjecting the oxidizedproduct of step (b) to a saponification treatment.
 6. The method ofclaim 5 wherein said saponification treatment comprises contacting saidproduct with a basic solution.
 7. The method of a claim 6 wherein saidbasic solution comprises sodium hydroxide.
 8. The method of claim 6additionally comprising the step of neutralizing the saponified productwith an acid.
 9. The method of claim 8 wherein said acid is hydrochloricacid.
 10. The method of claim 8 additionally comprising the step ofrecovering a solid product from the saponified, neutralize product. 11.The method of claim 10 wherein said product is recovered by a methodselected from the group consisting of filtration, settling by gravity,chemical flocculators, and liquid cycloning.
 12. The method of claim 10wherein said solid product is a paper-like two dimensional product. 13.The method of claim 12 additionally comprising the step of drying theproduct.
 14. The method of claim 13 wherein said product is dried atabout 850° C. in a hydrogen gas atmosphere.
 15. The method of claim 1wherein said product comprises at least about 90% by weight ofsingle-wall carbon nanotubes.
 16. The method of claim 1 wherein saidproduct comprises at least about 95% by weight of single-wall carbonnanotubes.
 17. The method of claim 1 where said product comprises atleast about 99% by weight of single-wall carbon nanotubes.
 18. A methodfor producing tubular carbon molecules of about 5 to 500 nm in length,said method comprising the steps of: (a) single-wall nanotubecontaining-material to form a more of tubular carbon molecules havinglengths in the range of 5-500 nm; (b) isolating from said mixture ofcarbon molecules a fraction of said molecules having substantially equallengths.
 19. The method of claim 18 wherein said cutting single-wallnanotubes into tubular carbon molecules comprising the steps of: (a)forming a substantially two-dimensional target containing single-wallnanotubes of lengths up to about one micron or more, and (b) irradiatingsaid target with a high energy beam of high mass ions.
 20. The method ofclaim 19 wherein said high energy beam is produced in a cyclotron andhas an energy of from about 0.1 to about 10 GeV.
 21. The method of claim19 wherein said high mass ion has a mass of greater than about 150 AMU.22. The method of claim 21 wherein said high mass ion is selected fromthe group consisting of gold, bismuth and uranium.
 23. The method ofclaim of 22 wherein the high mass ion is Au⁺³³.
 24. The method of claim18 wherein said cutting single-wall nanotubes into tubular carbonmolecules comprises the steps of: (a) forming a suspension ofsingle-wall nanotubes in a medium; (b) sonicating said suspension withacoustic energy.
 25. The method of claim 24 wherein said acoustic energyis produced by a device operating at 40 KHz and having an output of 20W.
 26. The method of claim 18 wherein said cutting single-wall nanotubesinto tubular carbon molecules comprises refluxing single wall nanotubematerial in concentrated HNO₃.
 27. The method of claim 19 furthercomprising the step of heating the tubular carbon molecules to form ahemispheric fullerene cap on at least one end thereof.
 28. The method ofclaim 18 further comprising the step of reacting said tubular carbonmolecules with a material which provides at the reaction conditions atleast one substituent on at least one of said ends of said tubularcarbon molecule.
 29. The method of claim 26 further comprising the stepof reacting said tubular carbon molecules with a material which providesat the reaction conditions at least one substituent on at least one ofsaid ends of said tubular carbon molecule.
 30. The method of claim 28 or29 wherein said substituent is selected from the group consisting ofeach may be independently selected from the group consisting ofhydrogen; alkyl, acyl, aryl, aralkyl, halogen; substituted orunsubstituted thiol; unsubstituted or substituted amino; hydroxy, andOR′ wherein R′ is selected from the group consisting of hydrogen, alkyl,acyl, aryl aralkyl, unsubstituted or substituted amino; substituted orunsubstituted thiol; and halogen; and a linear or cyclic carbonoptionally interrupted with one or more heteroatom, and optionallysubstituted with one or more ═O, or ═S, hydroxy, an aminoalkyl group, anamino acid, or a peptide of 2-8 amino acids.
 31. A method for forming amacroscopic molecular array of tubular carbon molecules, said methodcomprising the steps of: (a) providing at least about 10⁶ tubular carbonmolecules of substantially similar length in the range of 50 to 500 nm;(b) introducing a linking moiety onto at least one end of said tubularcarbon molecules; (c) providing a substrate coated with a material towhich said linking moiety will attach, and (d) contracting said tarcarbon molecules containing a linking moiety with said substrate. 32.The method of claim 31 wherein said substrate is selected from the groupconsisting of gold, mercury and indium-tin-oxide.
 33. The method ofclaim 32 wherein said lining moiety is selected from the groupconsisting of —S—, —S—(CH₂)₃—NH—, and —SiO₃(CH₂)₃NH₃.
 34. A method forforming a macroscopic molecular array of tubular carbon molecules, saidmethod comprising the steps of: (a) providing a nanoscale array ofmicrowells on a substrate; (b) depositing a metal catalyst in each ofsaid microwells; and (c) directing a stream of hydrocarbon or COfeedstock gas at said substrate under conditions that effect growth ofsingle-wall carbon nanotubes from each microwell.
 35. The method ofclaim 34 further comprising the step of applying an electric field inthe vicinity of said substrate to assist in the alignment of saidnanotubes growing from said microwells.
 36. A method for forming amacroscopic molecular array of tubular carbon molecules, said methodcomprising the steps of: (a) providing He containing purified butentangled and relatively endless single-wall carbon nanotube material;(b) subjecting said surface to oxidizing conditions sufficient to causeshort lags of broken nanotubes to protrude up from said surface; and (c)applying an electric field to said surface to cause said nanotubesprotruding from said surface to align in an orientation generallyperpendicular to said surface and coalesce into an array by van derWaals interaction forces.
 37. The method of claim 36 wherein saidoxidizing conditions comprise heating said surface to about 500° C. inan atmosphere of oxygen and CO₂.
 38. A method of forming a macroscopicmolecular array of tubular carbon molecules, said method comprising thestep of assembling subarrays of up to 10⁶ single-wall carbon nanotubesinto a composite array.
 39. The method of claim 38 wherein all thesubarrays have the same type of nanotubes.
 40. The method of claim 38wherein the subarrays have different types of nanotubes.
 41. The methodof claim 38 wherein the subarrays are made according to the method ofany of claims 31, 34 or
 36. 42. A method for continuously growingmacroscopic carbon fiber comprising at least about 10⁶ single-wallnanotubes in generally parallel orientation, said method comprising thesteps of: (a) providing a macroscopic molecular array of at least about10⁶ tubular carbon molecules in generally parallel orientation andhaving substantially similar lengths in the range of from about 50 toabout 500 nanometers; b) removing the hemispheric fullerene cap from theupper ends of the tubular carbon molecules in said array; (c) contactingsaid upper ends of the tubular carbon molecules in said array with atleast one catalytic metal; (d) supplying a gaseous source of carbon tothe end of said array while applying localized energy to the end of saidarray to heat said end to a temperature in the range of about 500° C. toabout 1300° C.; and (e) continuously recovering the growing carbonfiber.
 43. The method of claim 42 wherein said fullerene caps areremoved by heating in an oxidative environment.
 44. The method of claim43 wherein said oxidative environment comprises aqueous etching withnitric acid or gas phase etching at temperatures of about 500° C. In anatmosphere of oxygen and CO₂.
 45. The method of claim 42 wherein saidcambric metal is selected from the group consisting of Group VIIItransition metals, Group VI transition metals, metals of the lanthanideseries, metals of the actinide series, and mixtures thereof.
 46. Themethod of claim 45 wherein said catalytic metal is selected from thegroup consisting of Fe, Co, Ni, Ru, Rh, Pd, Os, Ir and Pt.
 47. Themethod of clam 46 wherein said catalytic metal is selected from thegroup consisting of Fe, Ni, and Co, and mixtures thereof.
 48. The methodof claim 45 wherein said catalytic metal is selected from the groupconsisting of Cr, Mo, and W.
 49. The method of claim 42 wherein saidcatalytic metal is deposited in situ on each nanotube as a metal atomcluster.
 50. The method of claim 49 wherein said metal atom cluster hasfrom about 10 to about 200 metal atoms.
 51. The method of claim 42wherein said catalytic metal is deposited as preformed nanoparticles.52. The method of claim 51 wherein said catalytic metal is Mo.
 53. Themod of claim 42 wherein said catalytic metal is deposited in the form ofa metal precursor selected from the group consisting of salts, oxidesand complexes of said metal.
 54. The method of claim 42 wherein saidcatalytic metal is deposited by evaporating metal atoms and allowingthem to condense and coalesce on said open nanotube ends.
 55. The methodof claim 54 wherein said evaporation is effected by heating a wire orwires containing said catalytic metal.
 56. The method of claim 54wherein said evaporation is effected by molecular beam evaporation. 57.The method of claim 42 wherein gaseous source of carbon is selected fromthe group consisting of hydrocarbons and carbon monoxide.
 58. The methodof claim 57 wherein said hydrocarbon is selected from the groupconsisting of alkyls, acyls, aryls and aralkyl having 1 to 7 carbonatoms.
 59. The method of claim 58 wherein said hydrocarbon is methane,ethane, ethylene, acetylene, acetone, propane, propylene and mixturesthereof.
 60. The method of claim 42 wherein said localized energy isprovided by a laser beam.
 61. The method of claim 42 wherein saidlocalized energy is provided by a source selected-from the groupconsisting of a microwave generator, an R-F coil and a solarconcentrator.
 62. The method of claim 42 wherein said end is heated to atemperature in the range of about 900° C. to about 1100° C.
 63. Acomposition of matter comprising at least about 80% by weight ofsingle-wall carbon nanotubes.
 64. The composition of claim 63 comprisingat least about 90% by weight of single-wall carbon nanotubes.
 65. Thecomposition of claim 63 comprising at least about 95% by weight ofsingle-wall carbon nanotubes.
 66. The composition of claim 63 comprisingat least about 99% by weight of single-wall carbon molecules.
 67. Asubstantially two-dimensional article comprising at least about 80% byweight of single-wall carbon nanotubes.
 68. The article of claim 67comprising at least about 90% by weight of single-wall nanotubes. 69.The article of claim 67 comprising at least about 95% by weight ofsingle-wall nanotubes.
 70. The article of claim 67 comprising at leastabout 99% by weight of single-wall nanotubes.
 71. The article of claim67 in the form of a paper-like material.
 72. A tubular carbon moleculehaving the following structure:

where

is a substantially defect-free cylindrical graphene sheet (optionallydoped with noncarbon atoms) having from about 10² to 10⁶ carbon atoms:where

is a hemispheric fullerene cap having at least six pentagons and theremainder hexagons; n is a number from 0 to 30; and R, R¹, R², R³, R⁴,and R⁵ each may be independently selected from the group consisting ofhydrogen; alkyl, acyl, aryl, aralkyl, halogen; substituted orunsubstituted thiol; unsubstituted or substituted, amino; hydroxy, andOR′ wherein R′ is selected from the group consisting of hydrogen, alkyl,acyl, aryl aralkyl, unsubstituted or substituted amino; substituted orunsubstituted thiol; and halogen; and a linear or cyclic carbon chainoptionally interrupted with one or more heteroatom, and optionallysubstituted with one or more ═O, or ═S, hydroxy, an aminoalkyl group, anamino acid, or a peptide of 2-8 amino acids.
 73. The molecule of claim72 wherein said graphene sheet has a configuration that corresponds to a(n, n) single-wall carbon nanotube.
 74. The molecule of claim 72 whereinsaid molecule has a length from about 5 to about 1000 nm.
 75. Themolecule of claim 74 wherein said molecule has a length of from about 5to about 500 mm.
 76. The molecule of claim 72 wherein n is 0 to
 12. 77.The molecule of claim 72 further using at least one endohedral species.78. The molecule of claim 77 wherein said endohedral species is selectedfrom the group consisting of metal atoms, fullerene molecules, othersmall molecules and mixture thereof.
 79. The molecule of claim 78comprising a (10, 10) single-wall nanotube containing at last oneendohedral species selected from the group consisting of C₆₀, C₇₀, ormixtures thereof.
 80. The molecule of claim 79 wherein said C₆₀ or C₇₀additionally contains an endohedral substituent selected from the groupconsisting of metal atoms and metal compounds.
 81. A macroscopicmolecular array comprising at least about 10⁶ single-wall carbonnanotubes in generally parallel orientation and having substantiallysimilar lengths in the range of from about 5 to about 500 nanometers.82. The array of claim 81 wherein said nanotubes are of the same type.83. The array of claim 82 wherein said nanotubes are of the (n, n) type.84. The array of claim 83 wherein said nanotubes are of the (10, 10)type.
 85. The array of claim 83 wherein said nanotubes are of the (m, n)type.
 86. The array of claim 81 wherein said nanotubes are of differenttypes.
 87. The array of claim 81 further comprising a substrate attachedto one end of said and oriented substantially perpendicularly to thenanotubes in said array.
 88. The array of claim 87 wherein saidsubstrate is a bucky paper surface.
 89. The array of claim 87 whereinsaid substrate is a metal layer selected from the group consisting ofgold, mercury and indium-tin-oxide.
 90. The array of claim 86 wherein acentral portion of nanotubes are of the (n, n) type and an outer portionof nanotubes are of the (m, n) type.
 91. A macroscopic carbon fibercomprising at least about 10⁶ single-wall carbon nanotubes in generallyparallel orientation.
 92. The fiber of claim 91 comprising at leastabout 10⁹ single-wall carbon nanotubes.
 93. A composite fiber comprisinga plurality of the fibers of claim
 91. 94. A molecular template arrayfor growing continuous length carbon fiber comprising a segment of thefiber of claim
 91. 95. The fiber of claim 91 having a length of at least1 millimeter.
 96. The fiber of claim 91 wherein a substantial portion ofsaid nanotubes are of the (n, n) type.
 97. The fiber of claim 91 whereinall of said nanotubes are not of the same type.
 98. A composite articleof manufacture comprising a matrix material selected from the groupconsisting of metals, polymers, ceramics and cermets, said matrix havingembedded in at least a portion thereof a property enhancing amount ofthe carbon fibers of claim
 91. 99. The composite article of claim 98wherein said property is structural, mechanical electrical, chemical,optical, or biological.
 100. A high voltage power transmission cablewherein at least one conductor comprises a continuous carbon fiberaccording to claim
 96. 101. The power transmission cable of claim 100wherein both a central conductor and a coaxially disposed outerconductor are formed from said carbon fiber and an insulating layer isdisposed therebetween.
 102. The power transmission cable of claim 101wherein said insulating layer is an air space.
 103. The powertransmission cable of claim 101 wherein said insulating layer comprisesa material selected from the group consisting of insulating carbon fibermade from carbon nanotubes of the (m, n) type and insulating BN fibermade from hexaboronitride nanotubes or mixtures thereof.
 104. A solarcell for converting broad spectrum light energy into electrical currentcomprising a molecular array according to claim 81 as the photoncollector.
 105. The solar cell of claim 104 additionally comprising aphotoactive dye coupled to the upper ends of the nanotubes in saidarray.
 106. A bistable, nonvolatile memory bit comprising theendohedrally-loaded tubular carbon molecule of claim
 77. 107. The memorybit of claim 106 wherein the tubular carbon molecule is formed from a(10, 10) type nanotube and the endohedral species is a C₆₀ or C70fullerene molecule.
 108. A bistable, nonvolatile memory devicecomprising the memory bit of claim 106, means for writing to said bitand means for reading said bit.
 109. The memory device of claim 108wherein said means for writing comprises a nanocircuit element adaptedto direct a voltage pulse of positive or negative polarity at said bitto cause said endohedral species to move from a first end to a secondend of said bit.
 110. The memory device of claim 108 wherein said meansfor reading said bit comprises (a) a first nanocircuit element adaptedto be biased at a first voltage (V_(Read)) and spaced from a read end ofsaid bit to form a first gap therebetween; and (b) a second nanocircuitelement adapted to be biased to ground voltage (V_(G)) and spaced fromsaid read end of said bit to form a second gap, whereby the presence ofsaid endohedral species is unambiguously determined by the presence ofcurrent tunneling across said first and second gaps.
 111. A microporousanode for an electrochemical cell comprising a molecular array accordingto claim
 81. 112. A lithium ion so battery comprising the anode of claim111, a cathode comprising LiCoO₂ and an aprotic organic electrolytewherein a fullerene intercalating compound (EC) of lithium forms at theanode under charging conditions.
 113. An apparatus for forming acontinuous macroscopic carbon fiber from a macroscopic moleculartemplate array comprising at least about 10⁶ single-wall carbonnanotubes having a catalytic metal deposited on the open ends of saidnanotubes, said apparatus comprising: (a) means for locally heating onlysaid open ends of said nanotubes in said template array in a growth andannealing zone to a temperature in the range of about 500° C. to 1300°C. (b) means for supplying a carbon-containing feedstock gas to thegrowth and annealing zone immediately adjacent said heated open ends ofsaid nanotubes in said template array, and (c) means for continuouslyremoving growing carbon fiber from said growth and annealing zone whilemaintaining the growing open end of said fiber in said growth andannealing zone.
 114. The apparatus of claim 113 wherein said means forlocally heating comprises a laser.
 115. The apparatus of claim 113enclosed in a growth chamber maintained at a vacuum by evacuation means.116. The apparatus of claim 115 further comprising a vacuum feed lockzone through which said continuously produced, carbon fiber is passedand a take-up roll at atmospheric pressure.
 117. A composite materialcomprising: (a) a matrix; and (b) a carbon nanotube material embeddedwithin said matrix.
 118. The composite material of claim 117, whereinsaid matrix comprises a polymer.
 119. The composite material of claim118, wherein said polymer comprises a thermosetting, polymer.
 120. Thecomposite material of claim 119, wherein said thermosetting polymer isselected from the group consisting of phthalic/maelic type polyesters,vinyl esters, epoxies, phenolics, cyanates, bismaleimides, and nadicend-capped polyimides.
 121. The composite material of claim 118, whereinsaid polymer comprises a thermoplastic polymer.
 122. The compositematerial of claim 121, wherein said thermoplastic polymer is selectedfrom the group consisting of polysulfones, polyamides, polycarbonatespolyphenylene oxides, polysulfides, polyether ether ketone, polyethersulfones, polyamide-imides, polyetherimides, polyimides, polyarylates,and liquid crystalline polyesters.
 123. The composite material of claim117, wherein said matrix comprises a metal.
 124. The composite materialof claim 117, wherein said matrix comprises a ceramic.
 125. Thecomposite material of claim 117, wherein said matrix comprises cermet.126. The composite material of claim 117, wherein said carbon nanotubematerial comprises tubular carbon nanotube molecules.
 127. The compositemat of claim 117, wherein said carbon nanotube material comprises ropesup to about 10³ SWNTs.
 128. The composite medial of claim 117, whereinsaid carbon nanotube material comprises fibers of greater than 10⁶SWNTs.
 129. The composite material of claim 126, 127, or 128, furthercomprising an additional fibrous material.
 130. The composite materialof claim 126, 127, or 128, wherein said carbon nanotube material ismodified to interact with said matrix material.
 131. A method forproducing a composite material containing carbon nanotube materialcomprising: (a) preparing a matrix material precursor; (b) combining acarbon nanotube material with said matrix material precursor; and (c)forming said composite material.
 132. The method of claim 131, whereinsaid carbon nanotube material is combined with said matrix materialprecursor before said step of forming.
 133. The method of claim 131,wherein said carbon nanotube material is combined with said matrixmaterial precursor during said step of forming.
 134. The method of claim131, wherein said carbon nanotube material is combined with said matrixmaterial precursor Mediately after said step of forming.
 135. The methodof claim 131, wherein said matrix material precursor is caused to flowaround a preformed arrangement of said carbon nanotube material.
 136. Amethod of producing a composite material containing carbon nanotubematerial comprising: (a) preparing an assembly of a fibrous material;(b) adding said carbon nanotube material to said fibrous material; and(c) adding a matrix material precursor to said carbon nanotube materialand said fibrous material.
 137. The method of claim 136, wherein saidfibrous materials are arranged in a two-dimensional sheet, and someportion of the said carbon nanotube material is oriented in a directionother than parallel to said sheet.
 138. The method of claim 131 or 136wherein said carbon nanotube material comprises tubular carbon nanotubemolecules.
 139. The method of claim 131 or 136 wherein said carbonnanotube material comprises ropes of up to about 10³ SWNTs.
 140. Themethod of claim 131 or 136 wherein said carbon nanotube materialcomprises fibers of greater than 10⁶ SWNTs.
 141. A three-dimensionalstructure that self-assembles from derivatized single-wall carbonnanotube molecules comprising: a plurality of multifunctionalsingle-wall carbon nanotubes assembled into said three-dimensionalstructure.
 142. The three-dimensional structure of claim 141, whereinsaid single-wall carbon nanotubes have multifunctional derivatives ontheir end caps.
 143. The three-dimensional structure of claim 141,wherein said single-wall carbon nanotubes have multifunctionalderivatives at multiple locations on said single-wall carbon nanotubes.144. The three-dimensional structure of claim 141, wherein saidsingle-wall carbon nanotubes are assembled as a result of van der Waalsattractions.
 145. A three-dimensional structure of claim 141, which haselectromagnetic properties.
 146. The three-dimensional structure ofclaim 145, wherein said electromagnetic properties are determined by afunctionally-specific agent.
 147. A three-dimensional structure of claim141, which is symmetrical.
 148. A three-dimensional structure of claim141, which is not symmetrical.
 149. A three-dimensional structure ofclaim 141, which has biological properties.
 150. A three-dimensionalstructure of claim 149, which operates as a catalyst for biochemicalreactions.
 151. A three-dimensional structure of claim 149, whichinteracts with living tissue.
 152. A three-dimensional structure ofclaim 149, which serves as an agent for interaction with functions of abiological system.
 153. A light harvesting antenna comprising: at leastone single-wall carbon nanotube conductive element, said at least onenanotube having a length selected relative to a desired current leveland a desired voltage level.
 154. The light harvesting antenna of claim153, wherein said at least one single-wall carbon nanotube forms aSchottky barrier.
 155. An array of light harvesting antennas of claim153.
 156. The array of light harvesting antennas of claim 155, whereinsaid array is formed by self-assembly.
 157. A molecular electroniccomponent comprising at least one single-wall carbon nanotube.
 158. Themolecular electronic component of claim 157, wherein said molecularelectronic component is a bridge circuit for providing full waverectification, said bridge circuit comprising: four single-wall carbonnanotubes, each of said four single-wall carbon nanotubes forming oneedge of a square and linked to two of four buckyballs, each of said fourbuckyballs located at a corner of said square.
 159. The bridge circuitof claim 158, wherein said buckyballs and single-wall carbon nanotubesare derivitized to include functionally specific linking agents.
 160. Amolecular electronic component of claim 157, which is a fullerene diode.161. A nanoscale manipulator comprising at least one single-wall carbonnanotube.
 162. The nanoscale manipulator of claim 161, which isnanoforcepts.